U.S. patent number 10,159,061 [Application Number 15/618,997] was granted by the patent office on 2018-12-18 for resource selection for device to device discovery or communication.
This patent grant is currently assigned to InterDigital Patent Holdings, Inc.. The grantee listed for this patent is INTERDIGITAL PATENT HOLDINGS, INC.. Invention is credited to Samian Kaur, Paul Marinier, Diana Pani, Benoit Pelletier, Ghyslain Pelletier, Yuxin Zhao.
United States Patent |
10,159,061 |
Zhao , et al. |
December 18, 2018 |
Resource selection for device to device discovery or
communication
Abstract
A wireless transmit receive unit (WTRU) may perform provide a
report to a network. The WTRU may include a processor that is
configured to receive a measurement configuration from the network,
where the measurement configuration indicates a threshold and a
resource pool on which to perform measurements. The resources pool
may be used for communication between one or more mobile device.
The processor may be configured to perform measurements on the
resource pool and determine whether an energy level for the
resource pool is above the threshold for a duration of time. The
processor may also be configured to send a report to the network
indicating that the energy level for the resource pool is above the
threshold for the predetermined duration of time.
Inventors: |
Zhao; Yuxin (Linkoping,
SE), Pani; Diana (Montreal, CA), Pelletier;
Ghyslain (Montreal, CA), Marinier; Paul
(Brossard, CA), Pelletier; Benoit (Roxboro,
CA), Kaur; Samian (Plymouth Meeting, PA) |
Applicant: |
Name |
City |
State |
Country |
Type |
INTERDIGITAL PATENT HOLDINGS, INC. |
Wilmington |
DE |
US |
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Assignee: |
InterDigital Patent Holdings,
Inc. (Wilmington, DE)
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Family
ID: |
52484566 |
Appl.
No.: |
15/618,997 |
Filed: |
June 9, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170280423 A1 |
Sep 28, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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14609188 |
Jan 29, 2015 |
9693338 |
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62075768 |
Nov 5, 2014 |
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61990046 |
May 7, 2014 |
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61955746 |
Mar 19, 2014 |
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61933238 |
Jan 29, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
56/002 (20130101); H04W 72/02 (20130101); H04W
72/04 (20130101); H04W 8/005 (20130101); H04W
72/082 (20130101); H04W 88/04 (20130101); H04W
24/10 (20130101); H04W 76/14 (20180201) |
Current International
Class: |
H04W
72/04 (20090101); H04W 72/08 (20090101); H04W
8/00 (20090101); H04W 72/02 (20090101); H04W
88/04 (20090101); H04W 76/14 (20180101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3120641 |
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Jan 2017 |
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EP |
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2014-007745 |
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Jan 2014 |
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JP |
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2503153 |
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Dec 2013 |
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RU |
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WO 2011/069295 |
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Jun 2011 |
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WO |
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WO 2013/123637 |
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Aug 2013 |
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WO |
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WO 2014/169695 |
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Oct 2014 |
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WO |
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Other References
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Structure for Relay Type 1 Nodes", NEC Group, TSG-RAN WG1#57Bis,
Los Angeles, CA, US, Jun. 29-Jul. 3, 2009, 5 pages. cited by
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Communication", Fujitsu, 3GPP TSG-RAN1 #75, San Francisco, United
States, Nov. 11-15, 2013, 6 pages. cited by applicant .
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Proximity Services--Radio Aspects, (Release 12)", Nov. 2013, pp.
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RAN-63, Fukuoka, Japan, Mar. 3-6, 2014, 40 pages. cited by
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R3-140047,"Discussion on the Coordination of D2D Resource for
Inter-Cell D2D Discovery and Communication", ZTE, 3GPP TSG-RAN WG3
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1-33 pages. cited by applicant.
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Primary Examiner: Mew; Kevin D
Attorney, Agent or Firm: Condo Roccia Koptiw LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No.
14/609,188, filed Jan. 29, 2015, which claims the benefit of U.S.
Provisional Application No. 61/933,238, filed Jan. 29, 2014, U.S.
Provisional Application No. 61/955,746, filed Mar. 19, 2014, U.S.
Provisional Application No. 61/990,046, filed May 7, 2014, and U.S.
Provisional Application No. 62/075,768, filed Nov. 5, 2014, the
disclosures of which are incorporated herein by reference in their
entirety.
Claims
What is claimed is:
1. A wireless transmit receive unit (WTRU) comprising: a processor
configured to: receive a measurement configuration from a network,
the measurement configuration indicating a threshold and a resource
pool on which to perform measurements, wherein the resource pool is
configured for direct communications between multiple WTRUs, and
the resource pool comprises a plurality of resources; measure
respective energy levels of the resources in the resource pool;
determine a ratio of the resources in the resource pool that have a
measured energy level above the threshold for a duration of time;
and send a report to the network indicating the ratio.
2. The WTRU of claim 1, wherein the resource pool comprises
sidelink resources.
3. The WTRU of claim 1, wherein the resource pool comprises
physical sidelink control channel (PSCCH) resources.
4. The WTRU of claim 1, wherein the resource pool comprises
resources used for device-to-device (D2D) discovery.
5. The WTRU of claim 1, wherein the ratio indicates a percentage of
the resources of the resource pool that is occupied.
6. The WTRU of claim 1, wherein, when the ratio exceeds a specific
level, the report indicates that the resources in the resource pool
are insufficient for the WTRU to meet a target QoS or discovery
transmission rate.
7. The WTRU of claim 1, wherein the report comprises an indication
of a number of subframes during which the respective measured
energy levels of the resources in the resource pool are above the
threshold.
8. The WTRU of claim 1, wherein the measurement configuration is
received via radio resource control (RRC) signaling.
9. A method comprising: receiving a measurement configuration from
a network, the measurement configuration indicating a threshold and
a resource pool on which to perform measurements, wherein the
resource pool is configured for direction communications between
multiple wireless transmit receive units (WTRUs), and the resource
pool comprises a plurality of resources; measure respective energy
levels of the resources in the resource pool; determining a ratio
of the resources in the resource pool that have a measured energy
level above the threshold for a duration of time; and sending a
report to the network indicating the ratio.
10. The method of claim 9, wherein the resource pool comprises
sidelink resources.
11. The method of claim 9, wherein the resource pool comprises
physical sidelink control channel (PSCCH) resources.
12. The method of claim 9, wherein the resource pool comprises
resources used for device-to-device (D2D) discovery.
13. The method of claim 9, wherein the ratio indicates a percentage
of the resources of the resource pool that is occupied.
14. The method of claim 9, wherein, when the ratio exceeds a
specific level, the report indicates that the resources in the
resource pool are insufficient to meet a target QoS or discovery
transmission rate.
15. The method of claim 9, wherein the report comprises an
indication of a number of subframes during which the respective
measured energy levels of the resources in the resource pool are
above the threshold.
16. The method of claim 9, wherein the measurement configuration is
received via radio resource control (RRC) signaling.
Description
BACKGROUND
The proximity between devices may be determined using LTE
positioning. In Device-to-Device (D2D) neighbor discovery, two or
more devices may determine their relative proximity based on direct
radio communications. Additional interference may be introduced by
these D2D transmissions.
SUMMARY
Systems, methods, and instrumentalities are disclosed to manage
potential interference that may be caused by D2D communications. A
first WTRU may send a resource report to a network. The first WTRU
may receive one or more resources from the network for transmission
of a discovery signal. The first WTRU may send the discovery signal
to a second WTRU.
The resource report may include one or more of resources for
transmission for D2D communication, identity of a discovery
process, location information, outcome of a discovery process,
outcome of a transmission attempt, measured resource utilization,
network resource configuration information, and/or a number of
failures or successes on a resource.
The resource report may be sent by the first WTRU based on a
configuration of a WTRU (e.g., the first WTRU and/or the second
WTRU), a periodic schedule, an aperiodic schedule, a change in
operation status, an outcome of a discovery process, an outcome of
a discovery signal decoded by the second WTRU, and/or an outcome of
a transmission attempt by the first WTRU.
The one or more resources may be characterized by one or more of
timing information, frequency information, sequence information,
and a hopping pattern.
The first WTRU and the second WTRU may be served by the same
network element (e.g., eNB). The first WTRU may be served by a
first eNB and the second WTRU may be served by a second eNB. The
first WTRU may be served by an eNB and the second WTRU may be
out-of-coverage of the network. The first WTRU may be
out-of-coverage of the network and the second WTRU may be served by
an eNB.
A wireless transmit receive unit (WTRU) may include a processor.
The processor may be configured to perform one or more of the
following. The processor may determine to send information using a
device-to-device transmission via a resource pool from a plurality
of resource pools. Each resource pool may be associated with a
range of reference signal receive power (RSRP) values. The
processor may determine a RSRP measurement of a cell associated
with the WTRU. The processor may select a resource pool from the
plurality of resource pools based on the RSRP measurement of the
cell. The RSRP measurement of the cell may be within the range of
RSRP values associated with the selected resource pool. The
processor may send the information using the selected resource
pool.
The range of RRSP values associated with the selected resource pool
may include a low RSRP threshold and a high RSRP threshold. The
RSRP measurement of the cell may be between the low RSRP threshold
and the high RSRP threshold.
The processor may be further configured to select a resource from a
plurality of resources in the selected resource pool. The processor
may be configured to select the resource using a randomization
function or a pseudo-random function. The processor may be
configured to send the information on the selected resource. The
selected resource may include one or more subframes. The selected
resource may include one or more physical resource blocks
(PRBs).
The processor may be further configured to receive a configuration
via radio resource control (RRC) signaling and determine, based on
the configuration, that the selection of the resource pool is based
on RSRP. The configuration may identify the resource pool and the
range of RSRP values associated with the resource pool.
A method (e.g., a computer-implemented method) may include
determining (e.g., at a processor) to send information using a
device-to-device transmission via a resource pool from a plurality
of resource pools. Each resource pool may be associated with a
range of reference signal receive power (RSRP) values. The method
may include determining (e.g., via a processor) a RSRP measurement
of a cell associated with the WTRU. The method may include
selecting (e.g., by a processor) a resource pool from the plurality
of resource pools based on the RSRP measurement of the cell. The
RSRP measurement of the cell may be within the range of RSRP values
associated with the selected resource pool. The method may include
sending (e.g., via a transmitter) the information using the
selected resource pool.
The range of RRSP values associated with the selected resource pool
may include a low RSRP threshold and a high RSRP threshold. The
RSRP measurement may be between the low RSRP threshold and the high
RSRP threshold.
The method may include selecting a resource from a plurality of
resources in the selected resource pool. The method may include
selecting the resource using a randomization function or a
pseudo-random function. The method may include sending the
information on the selected resource.
The method may include determining that the device-to-device
transmission is a Type 1 device-to-device transmission. The Type 1
device-to-device transmission may be characterized by a WTRU
selecting the resource pool from the plurality of resource pools.
The Type 1 device-to-device transmission may be characterized by a
WTRU selecting a resource from a plurality of resources in the
selected resource pool. The method may include receiving a request
to send the information using the device-to-device transmission and
determining to send the information using the device-to-device
transmission in response to the request.
A wireless transmit receive unit (WTRU) may include a processor.
The processor may be configured for one or more of the following.
The processor may receive a device-to-device transmission request
to send information via a resource pool from a plurality of
resource pools. The processor may determine that selection of the
resource pool from the plurality of resource pools is based on
reference signal receive power (RSRP). The processor may receive a
RSRP threshold associated with at least one resource pool from the
plurality of resource pools. The processor may determine a RSRP
measurement of a base station. The processor may compare the RSRP
measurement of the base station with the RSRP threshold associated
with the at least one resource pool. The processor may select the
at least one resource pool to send the information via
device-to-device transmission when the RSRP measurement of the base
station is above the RSRP threshold. The processor may send the
information using the at least one resource pool when the at least
one resource pool is selected to send the information.
The selected resource pool may include a plurality of resources.
The processor may select a resource from the plurality of resources
based on a randomization function and send the information using
the selected resource. The resource may include a subframe or a
physical resource block (PRB). The processor may receive a system
information block (SIB) that identifies the at least one resource
pool and indicates the RSRP threshold associated with the at least
one resource pool. The RSRP threshold may be a low RSRP threshold
of an open-ended range of RSRP values or a high RSRP threshold of
the open-ended range of RSRP values.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a system diagram of an example communications system in
which one or more disclosed embodiments may be implemented.
FIG. 1B is a system diagram of an example wireless transmit/receive
unit (WTRU) that may be used within the communications system
illustrated in FIG. 1A.
FIG. 1C is a system diagram of an example radio access network and
an example core network that may be used within the communications
system illustrated in FIG. 1A.
FIG. 1D is a system diagram of another example radio access network
and another example core network that may be used within the
communications system illustrated in FIG. 1A.
FIG. 1E is a system diagram of another example radio access network
and another example core network that may be used within the
communications system illustrated in FIG. 1A.
FIG. 2 is a diagram of an example of intra-cell interference
between D2D links.
FIG. 3 is a diagram of an example of inter-cell interference
between D2D links and from a D2D link to a cellular link.
FIG. 4 is a diagram of an example of intra-cell interference from a
cellular link to D2D links.
FIG. 5 is a diagram of an example of a discovery occasion.
FIG. 6 is a diagram of an example of scenarios for in-coverage,
out-of-coverage, and partial coverage D2D discovery and/or
communications.
FIG. 7 is a diagram of an example scenario of communication between
an in-coverage WTRU and an out-of-coverage WTRU.
FIG. 8 is a diagram of an example of signaling that may be used for
an out-of-coverage WTRU to determine and/or drive resource
allocation.
FIG. 9 is a diagram of an example of signaling that may be used for
an eNB and/or an in-coverage WTRU to determine and/or drive
resource allocation.
FIG. 10 is a diagram of an example of resource allocation of
discovery resources across two eNBs, eNB A and eNB B.
DETAILED DESCRIPTION
A detailed description of illustrative embodiments will now be
described with reference to the various Figures. Although this
description provides a detailed example of possible
implementations, it should be noted that the details are intended
to be exemplary and in no way limit the scope of the
application.
FIG. 1A is a diagram of an example communications system 100 in
which one or more disclosed embodiments may be implemented. The
communications system 100 may be a multiple access system that
provides content, such as voice, data, video, messaging, broadcast,
etc., to multiple wireless users. The communications system 100 may
enable multiple wireless users to access such content through the
sharing of system resources, including wireless bandwidth. For
example, the communications systems 100 may employ one or more
channel access methods, such as code division multiple access
(CDMA), time division multiple access (TDMA), frequency division
multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier
FDMA (SC-FDMA), and the like.
As shown in FIG. 1A, the communications system 100 may include
wireless transmit/receive units (WTRUs) 102a, 102b, 102c, and/or
102d (which generally or collectively may be referred to as WTRU
102), a radio access network (RAN) 103/104/105, a core network
106/107/109, a public switched telephone network (PSTN) 108, the
Internet 110, and other networks 112, though it will be appreciated
that the disclosed embodiments contemplate any number of WTRUs,
base stations, networks, and/or network elements. Each of the WTRUs
102a, 102b, 102c, 102d may be any type of device configured to
operate and/or communicate in a wireless environment. By way of
example, the WTRUs 102a, 102b, 102c, 102d may be configured to
transmit and/or receive wireless signals and may include user
equipment (WTRU), a mobile station, a fixed or mobile subscriber
unit, a pager, a cellular telephone, a personal digital assistant
(PDA), a smartphone, a laptop, a netbook, a personal computer, a
wireless sensor, consumer electronics, and the like.
The communications systems 100 may also include a base station 114a
and a base station 114b. Each of the base stations 114a, 114b may
be any type of device configured to wirelessly interface with at
least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access
to one or more communication networks, such as the core network
106/107/109, the Internet 110, and/or the networks 112. By way of
example, the base stations 114a, 114b may be a base transceiver
station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B,
a site controller, an access point (AP), a wireless router, and the
like. While the base stations 114a, 114b are each depicted as a
single element, it will be appreciated that the base stations 114a,
114b may include any number of interconnected base stations and/or
network elements.
The base station 114a may be part of the RAN 103/104/105, which may
also include other base stations and/or network elements (not
shown), such as a base station controller (BSC), a radio network
controller (RNC), relay nodes, etc. The base station 114a and/or
the base station 114b may be configured to transmit and/or receive
wireless signals within a particular geographic region, which may
be referred to as a cell (not shown). The cell may further be
divided into cell sectors. For example, the cell associated with
the base station 114a may be divided into three sectors. Thus, in
one embodiment, the base station 114a may include three
transceivers, e.g., one for each sector of the cell. In another
embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and, therefore, may utilize
multiple transceivers for each sector of the cell.
The base stations 114a, 114b may communicate with one or more of
the WTRUs 102a, 102b, 102c, 102d over an air interface 115/116/117,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible
light, etc.). The air interface 115/116/117 may be established
using any suitable radio access technology (RAT).
More specifically, as noted above, the communications system 100
may be a multiple access system and may employ one or more channel
access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the
like. For example, the base station 114a in the RAN 103/104/105 and
the WTRUs 102a, 102b, 102c may implement a radio technology such as
Universal Mobile Telecommunications System (UMTS) Terrestrial Radio
Access (UTRA), which may establish the air interface 115/116/117
using wideband CDMA (WCDMA). WCDMA may include communication
protocols such as High-Speed Packet Access (HSPA) and/or Evolved
HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access
(HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).
In another embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement a radio technology such as Evolved UMTS
Terrestrial Radio Access (E-UTRA), which may establish the air
interface 115/116/117 using Long Term Evolution (LTE) and/or
LTE-Advanced (LTE-A).
In other embodiments, the base station 114a and the WTRUs 102a,
102b, 102c may implement radio technologies such as IEEE 802.16
(e.g., Worldwide Interoperability for Microwave Access (WiMAX)),
CDMA2000, CDMA2000 1.times., CDMA2000 EV-DO, Interim Standard 2000
(IS-2000), Interim Standard 95 (IS-95), Interim Standard 856
(IS-856), Global System for Mobile communications (GSM), Enhanced
Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the
like.
The base station 114b in FIG. 1A may be a wireless router, Home
Node B, Home eNode B, or access point, for example, and may utilize
any suitable RAT for facilitating wireless connectivity in a
localized area, such as a place of business, a home, a vehicle, a
campus, and the like. In one embodiment, the base station 114b and
the WTRUs 102c, 102d may implement a radio technology such as IEEE
802.11 to establish a wireless local area network (WLAN). In
another embodiment, the base station 114b and the WTRUs 102c, 102d
may implement a radio technology such as IEEE 802.15 to establish a
wireless personal area network (WPAN). In yet another embodiment,
the base station 114b and the WTRUs 102c, 102d may utilize a
cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.)
to establish a picocell or femtocell. As shown in FIG. 1A, the base
station 114b may have a direct connection to the Internet 110.
Thus, the base station 114b may not be required to access the
Internet 110 via the core network 106/107/109.
The RAN 103/104/105 may be in communication with the core network
106/107/109, which may be any type of network configured to provide
voice, data, applications, and/or voice over internet protocol
(VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d.
For example, the core network 106/107/109 may provide call control,
billing services, mobile location-based services, pre-paid calling,
Internet connectivity, video distribution, etc., and/or perform
high-level security functions, such as user authentication.
Although not shown in FIG. 1A, it will be appreciated that the RAN
103/104/105 and/or the core network 106/107/109 may be in direct or
indirect communication with other RANs that employ the same RAT as
the RAN 103/104/105 or a different RAT. For example, in addition to
being connected to the RAN 103/104/105, which may be utilizing an
E-UTRA radio technology, the core network 106/107/109 may also be
in communication with another RAN (not shown) employing a GSM radio
technology.
The core network 106/107/109 may also serve as a gateway for the
WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet
110, and/or other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another core network connected to one or
more RANs, which may employ the same RAT as the RAN 103/104/105 or
a different RAT.
Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities,
e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple
transceivers for communicating with different wireless networks
over different wireless links. For example, the WTRU 102c shown in
FIG. 1A may be configured to communicate with the base station
114a, which may employ a cellular-based radio technology, and with
the base station 114b, which may employ an IEEE 802 radio
technology.
FIG. 1B is a system diagram of an example WTRU 102. As shown in
FIG. 1B, the WTRU 102 may include a processor 118, a transceiver
120, a transmit/receive element 122, a speaker/microphone 124, a
keypad 126, a display/touchpad 128, non-removable memory 130,
removable memory 132, a power source 134, a global positioning
system (GPS) chipset 136, and other peripherals 138. It will be
appreciated that the WTRU 102 may include any sub-combination of
the foregoing elements while remaining consistent with an
embodiment. Also, embodiments contemplate that the base stations
114a and 114b, and/or the nodes that base stations 114a and 114b
may represent, such as but not limited to transceiver station
(BTS), a Node-B, a site controller, an access point (AP), a home
node-B, an evolved home node-B (eNodeB), a home evolved node-B
(HeNB), a home evolved node-B gateway, and proxy nodes, among
others, may include some or all of the elements depicted in FIG. 1B
and described herein.
The processor 118 may be a general purpose processor, a special
purpose processor, a conventional processor, a digital signal
processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Array (FPGAs) circuits, any other type of
integrated circuit (IC), a state machine, and the like. The
processor 118 may perform signal coding, data processing, power
control, input/output processing, and/or any other functionality
that enables the WTRU 102 to operate in a wireless environment. The
processor 118 may be coupled to the transceiver 120, which may be
coupled to the transmit/receive element 122. While FIG. 1B depicts
the processor 118 and the transceiver 120 as separate components,
it will be appreciated that the processor 118 and the transceiver
120 may be integrated together in an electronic package or
chip.
The transmit/receive element 122 may be configured to transmit
signals to, or receive signals from, a base station (e.g., the base
station 114a) over the air interface 115/116/117. For example, in
one embodiment, the transmit/receive element 122 may be an antenna
configured to transmit and/or receive RF signals. In another
embodiment, the transmit/receive element 122 may be an
emitter/detector configured to transmit and/or receive IR, UV, or
visible light signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
In addition, although the transmit/receive element 122 is depicted
in FIG. 1B as a single element, the WTRU 102 may include any number
of transmit/receive elements 122. More specifically, the WTRU 102
may employ MIMO technology. Thus, in one embodiment, the WTRU 102
may include two or more transmit/receive elements 122 (e.g.,
multiple antennas) for transmitting and receiving wireless signals
over the air interface 115/116/117.
The transceiver 120 may be configured to modulate the signals that
are to be transmitted by the transmit/receive element 122 and to
demodulate the signals that are received by the transmit/receive
element 122. As noted above, the WTRU 102 may have multi-mode
capabilities. Thus, the transceiver 120 may include multiple
transceivers for enabling the WTRU 102 to communicate via multiple
RATs, such as UTRA and IEEE 802.11, for example.
The processor 118 of the WTRU 102 may be coupled to, and may
receive user input data from, the speaker/microphone 124, the
keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal
display (LCD) display unit or organic light-emitting diode (OLED)
display unit). The processor 118 may also output user data to the
speaker/microphone 124, the keypad 126, and/or the display/touchpad
128. In addition, the processor 118 may access information from,
and store data in, any type of suitable memory, such as the
non-removable memory 130 and/or the removable memory 132. The
non-removable memory 130 may include random-access memory (RAM),
read-only memory (ROM), a hard disk, or any other type of memory
storage device. The removable memory 132 may include a subscriber
identity module (SIM) card, a memory stick, a secure digital (SD)
memory card, and the like. In other embodiments, the processor 118
may access information from, and store data in, memory that is not
physically located on the WTRU 102, such as on a server or a home
computer (not shown).
The processor 118 may receive power from the power source 134, and
may be configured to distribute and/or control the power to the
other components in the WTRU 102. The power source 134 may be any
suitable device for powering the WTRU 102. For example, the power
source 134 may include one or more dry cell batteries (e.g.,
nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride
(NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and
the like.
The processor 118 may also be coupled to the GPS chipset 136, which
may be configured to provide location information (e.g., longitude
and latitude) regarding the current location of the WTRU 102. In
addition to, or in lieu of, the information from the GPS chipset
136, the WTRU 102 may receive location information over the air
interface 115/116/117 from a base station (e.g., base stations
114a, 114b) and/or determine its location based on the timing of
the signals being received from two or more nearby base stations.
It will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination method
while remaining consistent with an embodiment.
The processor 118 may further be coupled to other peripherals 138,
which may include one or more software and/or hardware modules that
provide additional features, functionality and/or wired or wireless
connectivity. For example, the peripherals 138 may include an
accelerometer, an e-compass, a satellite transceiver, a digital
camera (for photographs or video), a universal serial bus (USB)
port, a vibration device, a television transceiver, a hands free
headset, a Bluetooth.RTM. module, a frequency modulated (FM) radio
unit, a digital music player, a media player, a video game player
module, an Internet browser, and the like.
FIG. 1C is a system diagram of the RAN 103 and the core network 106
according to an embodiment. As noted above, the RAN 103 may employ
a UTRA radio technology to communicate with the WTRUs 102a, 102b,
102c over the air interface 115. The RAN 103 may also be in
communication with the core network 106. As shown in FIG. 1C, the
RAN 103 may include Node-Bs 140a, 140b, 140c, which may each
include one or more transceivers for communicating with the WTRUs
102a, 102b, 102c over the air interface 115. The Node-Bs 140a,
140b, 140c may each be associated with a particular cell (not
shown) within the RAN 103. The RAN 103 may also include RNCs 142a,
142b. It will be appreciated that the RAN 103 may include any
number of Node-Bs and RNCs while remaining consistent with an
embodiment.
As shown in FIG. 1C, the Node-Bs 140a, 140b may be in communication
with the RNC 142a. Additionally, the Node-B 140c may be in
communication with the RNC 142b. The Node-Bs 140a, 140b, 140c may
communicate with the respective RNCs 142a, 142b via an Iub
interface. The RNCs 142a, 142b may be in communication with one
another via an Iur interface. Each of the RNCs 142a, 142b may be
configured to control the respective Node-Bs 140a, 140b, 140c to
which it is connected. In addition, each of the RNCs 142a, 142b may
be configured to carry out or support other functionality, such as
outer loop power control, load control, admission control, packet
scheduling, handover control, macrodiversity, security functions,
data encryption, and the like.
The core network 106 shown in FIG. 1C may include a media gateway
(MGW) 144, a mobile switching center (MSC) 146, a serving GPRS
support node (SGSN) 148, and/or a gateway GPRS support node (GGSN)
150. While each of the foregoing elements are depicted as part of
the core network 106, it will be appreciated that any one of these
elements may be owned and/or operated by an entity other than the
core network operator.
The RNC 142a in the RAN 103 may be connected to the MSC 146 in the
core network 106 via an IuCS interface. The MSC 146 may be
connected to the MGW 144. The MSC 146 and the MGW 144 may provide
the WTRUs 102a, 102b, 102c with access to circuit-switched
networks, such as the PSTN 108, to facilitate communications
between the WTRUs 102a, 102b, 102c and traditional land-line
communications devices.
The RNC 142a in the RAN 103 may also be connected to the SGSN 148
in the core network 106 via an IuPS interface. The SGSN 148 may be
connected to the GGSN 150. The SGSN 148 and the GGSN 150 may
provide the WTRUs 102a, 102b, 102c with access to packet-switched
networks, such as the Internet 110, to facilitate communications
between and the WTRUs 102a, 102b, 102c and IP-enabled devices.
As noted above, the core network 106 may also be connected to the
networks 112, which may include other wired or wireless networks
that are owned and/or operated by other service providers.
FIG. 1D is a system diagram of the RAN 104 and the core network 107
according to an embodiment. As noted above, the RAN 104 may employ
an E-UTRA radio technology to communicate with the WTRUs 102a,
102b, 102c over the air interface 116. The RAN 104 may also be in
communication with the core network 107.
The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will
be appreciated that the RAN 104 may include any number of eNode-Bs
while remaining consistent with an embodiment. The eNode-Bs 160a,
160b, 160c may each include one or more transceivers for
communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may
implement MIMO technology. Thus, the eNode-B 160a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
Each of the eNode-Bs 160a, 160b, 160c may be associated with a
particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the uplink and/or downlink, and the like. As shown in FIG.
1D, the eNode-Bs 160a, 160b, 160c may communicate with one another
over an X2 interface.
The core network 107 shown in FIG. 1D may include a mobility
management gateway (MME) 162, a serving gateway 164, and a packet
data network (PDN) gateway 166. While each of the foregoing
elements are depicted as part of the core network 107, it will be
appreciated that any one of these elements may be owned and/or
operated by an entity other than the core network operator.
The MME 162 may be connected to each of the eNode-Bs 160a, 160b,
160c in the RAN 104 via an S1 interface and may serve as a control
node. For example, the MME 162 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and the
like. The MME 162 may also provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM or WCDMA.
The serving gateway 164 may be connected to each of the eNode-Bs
160a, 160b, 160c in the RAN 104 via the S1 interface. The serving
gateway 164 may generally route and forward user data packets
to/from the WTRUs 102a, 102b, 102c. The serving gateway 164 may
also perform other functions, such as anchoring user planes during
inter-eNode B handovers, triggering paging when downlink data is
available for the WTRUs 102a, 102b, 102c, managing and storing
contexts of the WTRUs 102a, 102b, 102c, and the like.
The serving gateway 164 may also be connected to the PDN gateway
166, which may provide the WTRUs 102a, 102b, 102c with access to
packet-switched networks, such as the Internet 110, to facilitate
communications between the WTRUs 102a, 102b, 102c and IP-enabled
devices.
The core network 107 may facilitate communications with other
networks. For example, the core network 107 may provide the WTRUs
102a, 102b, 102c with access to circuit-switched networks, such as
the PSTN 108, to facilitate communications between the WTRUs 102a,
102b, 102c and traditional land-line communications devices. For
example, the core network 107 may include, or may communicate with,
an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that
serves as an interface between the core network 107 and the PSTN
108. In addition, the core network 107 may provide the WTRUs 102a,
102b, 102c with access to the networks 112, which may include other
wired or wireless networks that are owned and/or operated by other
service providers.
FIG. 1E is a system diagram of the RAN 105 and the core network 109
according to an embodiment. The RAN 105 may be an access service
network (ASN) that employs IEEE 802.16 radio technology to
communicate with the WTRUs 102a, 102b, 102c over the air interface
117. As will be further discussed below, the communication links
between the different functional entities of the WTRUs 102a, 102b,
102c, the RAN 105, and the core network 109 may be defined as
reference points.
As shown in FIG. 1E, the RAN 105 may include base stations 180a,
180b, 180c, and an ASN gateway 182, though it will be appreciated
that the RAN 105 may include any number of base stations and ASN
gateways while remaining consistent with an embodiment. The base
stations 180a, 180b, 180c may each be associated with a particular
cell (not shown) in the RAN 105 and may each include one or more
transceivers for communicating with the WTRUs 102a, 102b, 102c over
the air interface 117. In one embodiment, the base stations 180a,
180b, 180c may implement MIMO technology. Thus, the base station
180a, for example, may use multiple antennas to transmit wireless
signals to, and receive wireless signals from, the WTRU 102a. The
base stations 180a, 180b, 180c may also provide mobility management
functions, such as handoff triggering, tunnel establishment, radio
resource management, traffic classification, quality of service
(QoS) policy enforcement, and the like. The ASN gateway 182 may
serve as a traffic aggregation point and may be responsible for
paging, caching of subscriber profiles, routing to the core network
109, and the like.
The air interface 117 between the WTRUs 102a, 102b, 102c and the
RAN 105 may be defined as an R1 reference point that implements the
IEEE 802.16 specification. In addition, each of the WTRUs 102a,
102b, 102c may establish a logical interface (not shown) with the
core network 109. The logical interface between the WTRUs 102a,
102b, 102c and the core network 109 may be defined as an R2
reference point, which may be used for authentication,
authorization, IP host configuration management, and/or mobility
management.
The communication link between each of the base stations 180a,
180b, 180c may be defined as an R8 reference point that includes
protocols for facilitating WTRU handovers and the transfer of data
between base stations. The communication link between the base
stations 180a, 180b, 180c and the ASN gateway 182 may be defined as
an R6 reference point. The R6 reference point may include protocols
for facilitating mobility management based on mobility events
associated with each of the WTRUs 102a, 102b, 102c.
As shown in FIG. 1E, the RAN 105 may be connected to the core
network 109. The communication link between the RAN 105 and the
core network 109 may defined as an R3 reference point that includes
protocols for facilitating data transfer and mobility management
capabilities, for example. The core network 109 may include a
mobile IP home agent (MIP-HA) 184, an authentication,
authorization, accounting (AAA) server 186, and a gateway 188.
While each of the foregoing elements are depicted as part of the
core network 109, it will be appreciated that any one of these
elements may be owned and/or operated by an entity other than the
core network operator.
The MIP-HA may be responsible for IP address management, and may
enable the WTRUs 102a, 102b, 102c to roam between different ASNs
and/or different core networks. The MIP-HA 184 may provide the
WTRUs 102a, 102b, 102c with access to packet-switched networks,
such as the Internet 110, to facilitate communications between the
WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186
may be responsible for user authentication and for supporting user
services. The gateway 188 may facilitate interworking with other
networks. For example, the gateway 188 may provide the WTRUs 102a,
102b, 102c with access to circuit-switched networks, such as the
PSTN 108, to facilitate communications between the WTRUs 102a,
102b, 102c and traditional land-line communications devices. In
addition, the gateway 188 may provide the WTRUs 102a, 102b, 102c
with access to the networks 112, which may include other wired or
wireless networks that are owned and/or operated by other service
providers.
Although not shown in FIG. 1E, it will be appreciated that the RAN
105 may be connected to other ASNs and the core network 109 may be
connected to other core networks. The communication link between
the RAN 105 the other ASNs may be defined as an R4 reference point,
which may include protocols for coordinating the mobility of the
WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The
communication link between the core network 109 and the other core
networks may be defined as an R5 reference, which may include
protocols for facilitating interworking between home core networks
and visited core networks.
FIG. 2 is a diagram of an example of intra-cell interference
between D2D links. When two or more D2D transmitting WTRUs in the
same cell transmit signals (e.g., discovery signals) on the same
resource, interference 202, 204 may be introduced to the D2D
transmission in the cell.
FIG. 3 is a diagram of an example of inter-cell interference
between D2D links and from a D2D link to a cellular link. When a
cell edge D2D transmitting WTRU transmits a signal (e.g., a
discovery signal) using the same resources as one or more
transmitting WTRUs (e.g., a WTRU transmitting a D2D signal, a
cellular signal (e.g., such as an UL PUSCH), and/or the like in a
neighbor cell, interference 302 may be introduced to a signal, such
as a D2D signal 304 and/or a PUSCH transmission 306, in a neighbor
cell.
FIG. 4 is a diagram of an example of intra-cell interference from a
cellular link to one or more D2D links. When a cell edge cellular
transmitting WTRU transmits a signal (e.g., an UL PUSCH
transmission) using the same resources as a D2D transmitting WTRU
in a neighbor cell, interference 402 may be introduced to D2D
transmissions in the neighbor cell.
The interference between cellular UL transmission and D2D links may
be avoided by dedicating a number of subframes to D2D. The
interference between D2D links within the same cell as well as
cross neighbor cells may be managed.
Interference may be managed by means of resource allocation. For
example, by allocating resources properly, the probability that two
or more D2D WTRUs select the same resource may be reduced. For
example, the network may determine the amount of resources to
allocate to two or more D2D transmitting WTRUs. For example, the
network may determine which resources to allocate to which WTRU.
For example, D2D WTRU may select the resources to transmit a
discovery signal.
FIG. 5 is a diagram illustrating an example of a discovery
occasion. A discovery occasion may refer to a number of consecutive
subframes that may be reserved in a discovery period. The discovery
occasion may be used for discovery. The discovery period may refer
to a period of time between the start of two consecutive discovery
occasions. For example, the discovery period may be t seconds. The
discovery occasion cycle may refer to a set of N.sub.do>1
consecutive discovery occasions.
Network may refer to a node (e.g., any node) that is involved in
the control of the allocation of resources for a discovery signal
transmission. For example, the network may refer to an eNB, a ProSe
server, mobile device that may act as a centralized coordinating
entity for the D2D discovery function, and/or the like. One or more
embodiments provided herein may be provided in the context of
discovery. One or more embodiments provided herein may apply to a
direct device-to-device (D2D) communication. One or more
embodiments provided herein may be applicable to the data part of a
D2D communication. One or more embodiments provided herein may be
applicable to the control part of a D2D communication (e.g., the
SA, D2DSS, or other control signal). For example, one or more
embodiments provided herein may be applicable to Sidelink Control
Information (SCI) that may be carried on the Physical Sidelink
Control Channel (PSCCH) or to Sidelink Synchronization Signals that
may be carried on the Physical Sidelink Broadcast Channel
(PSBCH).
A transmitter WTRU may transmit a Scheduling Assignment (SA) that
may indicate, for example, resources (e.g., time and frequency, for
example subframe(s) and/or PRB(s)) used for transmission of D2D
data to a receiver WTRU, such as when WTRUs may be performing D2D
communications. For example, a transmitter WTRU may transmit D2D
data in resources that may be indicated by a Scheduling Assignment.
A receiving WTRU may determine resources (e.g., time and frequency)
to receive data based on, for example, the reception of a
Scheduling Assignment.
A D2DSS may be a device-to-device synchronization signal.
A WTRU may be configured with one or more independent discovery
processes. For example, a discovery process may be tied to a
specific application and/or may correspond to a specific discovery
signal that the WTRU transmits and/or receives. Examples provided
herein may be discovery process-specific and/or be applicable to
all discovery processes, e.g., at once. A WTRU may be configured
with one or more D2D communications processes. One or more
embodiments described herein may be applicable on a per-D2D
communication process basis. One or more embodiments described
herein may be applicable to a plurality of (e.g., all) D2D
communications processes, for example, at once. One or more
embodiments described herein may be applicable to certain D2D modes
of operation (e.g., Mode 1--eNB-controlled, Mode 2--distributed,
etc.) and/or to certain D2D coverage states (e.g., in-coverage,
edge-of-coverage, out-of-coverage).
A discovery signal may correspond to a D2D message that carries
information pertaining to, for example, a discovery process (e.g.,
proximity, discovery identities). A D2D message may carry, for
example, a data part of D2D communications. A D2D message may
carry, for example, Scheduling Assignment information that may be
used to perform a function (e.g., scheduling the data part of D2D
communications).
One or more embodiments described herein in the context of
discovery signals may be applicable to any D2D transmissions and/or
messages. Discovery signal, discovery signal resource,
measurements, etc. may be used interchangeably and/or applied to a
D2D message, D2D resources, or measurement.
One or more embodiments for resource allocation may be provided. A
WTRU may be allocated one or more resources for the transmission of
a discovery signal. A WTRU may be allocated one or more resources
for D2D transmissions (e.g., SA and/or data transmissions). A WTRU
may select one or more resources for D2D transmissions (e.g., SA
and/or data transmissions). Resource allocation may be
characterized by timing information (e.g. when is the resource
available, at the granularity of one transmission time interval
(TTI) and/or subframe), by frequency (e.g. carrier, set of PRBs
(physical resource blocks), and/or the like), by information (e.g.
where in frequency is the resource located, e.g. for one or more
subframes), by parameters that may determine how the signal is
transmitted and/or received (e.g. sequence, hopping pattern, and/or
the like), and/or the like. Timing information may include absolute
timing information, periodic allocation information, timing
information relative to another aspect of the discovery
configuration and/or process, and/or the like. Information relating
to resource allocation may be signaled (e.g., explicitly signaled)
and/or parameterized, for example, such that the WTRU may
implicitly calculate and/or determine the resource allocation
(e.g., in time and/or in frequency) and/or the WTRU may be
tabulated such that indices to one or more entries in a table(s)
may be exchanged.
The resource allocation may be structured, for example, such that
it may be represented as an indexed list of elements, for example,
where each element may correspond to a specific resource. For
example, a WTRU may be configured with a configuration index which
may represent one of a number X possible configurations for the
specific applicable frame structure (e.g., FDD or TDD when under
network coverage, a frame structure specific to a direct
WTRU-to-WTRU communication, and/or discovery operation). The
configuration index may refer to a tabulated value which may be
used by the WTRU to determine the set of resources available (e.g.,
in the cell). The WTRU may use this information to determine the
indexing of the resources.
The WTRU may be configured with a frequency offset (e.g., if the
resources span a subset of all the physical resource blocks (PRBs)
in a given subframe). The frequency offset may indicate the first
PRB of the resource for a given subframe. For a time interval
(e.g., a 10 ms frame, a time period of Y TTIs, Y ms, and/or Y radio
frames, etc.), the WTRU may determine what subframe includes a
resource and/or the location of the first PRB of the resource. The
resource may be indexed for a period (e.g., period Y) in increasing
order of the subframe number and/or of the PRB in the frequency
domain (e.g., if multiple resources may be multiplexed in frequency
for a given subframe). For example, the first resource in a period
Y may be allocated index 0, the second resource in the period Y may
be allocated index 1, and so on. The WTRU may be allocated
resources such that all resources in the set are available and/or
such that a subset of resources in the set may be available, for
example, by receiving (e.g., as part of the configuration) a
masking parameter and/or specific indices that represent the subset
of resources within the set of resources.
A resource for SA and/or its associated data transmission may
comprise an index to a plurality of frequency and/or PRB elements,
for example, in D2D communications. A WTRU may be configured to
repeat SA. A SA resource may comprise, for example, an associated
transmission pattern indicating information (e.g., frequency and/or
time location of a SA over a period of time). A scheduling period
may refer to the frequency and/or time location of a SA over a
period of time. A resource for data transmission may comprise an
associated transmission pattern. Data may not necessarily repeat.
Data may comprise transmission opportunities for a WTRU.
For example, a WTRU may be configured with one or more resources
for D2D communications. One or more resources for D2D
communications may be associated with a mode of operation (e.g.,
Mode 1, Mode 2, etc.). One or more resources for D2D communications
may be associated with a coverage state. For example, a WTRU may be
configured to report to an eNB for resources that may be in control
of an eNB, e.g., for a resource pool associated to operations
(e.g., in-coverage, edge-of-coverage operations).
WTRU measurement and reporting may be provided. The WTRU may
perform one or more measurements and report the one or more
measurements to the network (e.g., eNB), for example, to help the
network determine the amount of resources to allocate to the
WTRU.
An availability status of a resource may be determined based on a
measured energy level. The measured energy level may be compared
with a threshold to determine the availability status of the
resource.
A resource may be determined to be occupied and/or unavailable for
transmission. For example, a resource may be determined to be
occupied and/or unavailable for transmission when a measured energy
level on the resource is above a threshold. The resource may be
unavailable when a measured energy level on a resource is above a
threshold for a predefined period of time. The resource may be
unavailable when the WTRU determines that the resource is being
used by another WTRU, for example, by means of a received and/or
detected announcement message and/or control message, and/or the
like.
A resource may be determined to be available for transmission. For
example, a resource may be determined to be available for
transmission when a measured energy level is below a threshold. The
resource may be available when a measured energy level is below a
threshold for a predefined period of time. A resource that is
available may be used by the WTRU at any time (e.g., if allocated
by the network for that WTRU to transmit), and/or the like.
A discovery signal may be determined to be present on a resource. A
communication signal may be determined to be present on a resource.
For example, a signal (e.g., discovery signal and/or communication
signal) may be determined to be present on a resource when a
measured energy on the resource is above a defined threshold. For
example, the signal may be detected on the resource when a measured
energy on the resource is above a threshold for a period of time.
The signal may be detected on the resource when a discovery signal
is decoded successfully on the resource. The signal may be detected
on the resource when a control signal associated with a discovery
signal and/or communication signal (e.g., indicating the presence
of the discovery signal or communication signal) is decoded
successfully, and/or the like.
A WTRU may measure SA utilization by counting SAs (e.g.,
successfully received SAs) in a time frame. A determination may be
made that SA resources have been successfully received, for
example, if a WTRU decodes a SA and associated CRC checks. A SA may
be considered successfully received if the measured SNR is above a
threshold. The threshold may be determined (e.g., by tests,
configured, etc.). The WTRU may count SAs when the CRC is masked by
an identity that is unknown to a WTRU. An SA resource that is
successfully received may be considered utilized.
A WTRU may measure SA utilization by measuring energy in SA
resources. An SA resource may be considered utilized, for example,
if a WTRU measures the energy level in an SA resource location
(e.g., in time/frequency). An SA resource may be considered
utilized if a WTRU determines that the energy level in an SA
resource is above a threshold. A threshold may be predefined. A
threshold may be defined by other parameters (e.g., by tests or
configured).
A WTRU may measure near-far effect. A WTRU may determine near-far
effect. Near-far effect may impact, for example, the ability of a
WTRU to receive communications from other WTRUs (e.g., when the
signal strength of a WTRU may be stronger than the signal of other
WTRUs, when detection of a low received power signal is more
difficult than normal, and/or the like).
A WTRU may suffer from the near-far effect, for example, when a
WTRU receives signal from one or more WTRUs with a stronger power
than other WTRU signals. A WTRU may be configured to detect
examples of near-far effect by measuring the signal power of one or
more devices in the vicinity. A WTRU may be configured to detect
examples of near-far effect by determining whether one or more
signals in the vicinity has the potential to create near-far
effect. A WTRU may be configured to detect examples of near-far
effect by determining when one or more signals are stronger than
other signals by an amount, such as, for example, a predefined
amount or threshold.
A WTRU may determine D2D data resources based on, for example, D2D
data transmission patterns. A D2D data resource may comprise a
predefined pattern (e.g., in time, in frequency, or both). A WTRU
may be configured to measure for a D2D data pattern. A WTRU may be
configured to measure for an aggregate D2D data pattern (e.g., a
WTRU may be configured to report for all PRBs for a specific
time-based pattern).
The measure energy level may be weighted (e.g., divided, subtracted
in the dB domain, modified, and/or the like) by a thermal noise
measurement/estimate performed by the WTRU.
A WTRU may report the resource usage to the network. A WTRU may
perform transmissions, such as when a WTRU is configured with
resources for transmission (e.g., of a discovery signal, a D2D
transmission, or a D2D message). If the resource is dedicated to a
WTRU and/or discovery process, the outcome (e.g., of the discovery
or D2D transmissions) may be less likely impacted by interference
from other transmitting WTRUs. In this case, it may be assumed that
there is no other WTRU in proximity of the transmitting WTRU if no
other WTRU successfully receive the discovery signal from the
transmitting WTRU.
If the resource may be shared by a plurality of transmitting WTRUs
(e.g., for the same or for different discovery processes and/or D2D
transmissions), the outcome of the discovery may be impacted by
interference from other transmitting WTRUs that may contend for the
resource and/or that may be within proximity of each other. In such
case, it may not be possible to determine whether a monitoring WTRU
has not been successful in receiving the discovery signal or D2D
message, for example, because the received signal may be too weak
(e.g., the monitoring WTRU may not be within proximity of the
transmitting WTRU), because the level of interference is too high
(e.g. the monitoring WTRU may be within proximity of the
transmitting WTRU but the signal may not be detected with
sufficient signal to noise ratio), and/or the like. This may be
problematic for the network resource management, for example,
because there may not be means to determine if more resources are
needed for discovery/communications.
Collisions may occur in a resource that is shared by different
WTRUs and/or by the discovery processes. The network may allocate
one or more resources to a plurality of transmitting WTRUs. A
collision may occur for a concerned resource when more than one
transmitting WTRUs are transmitting a discovery signal. A collision
may occur for a concerned resource when a plurality of transmitting
WTRUs are transmitting a D2D message. The level of interference
generated may be a function of the distance between the
transmitting WTRUs that generate the collision on the concerned
resource and/or as a function of the relative distance of a
receiving WTRU to such transmitting WTRUs (e.g., when the signal
power received from the WTRUs has a ratio that trends towards 1).
The network may allocate resources by estimating the rate of
discovery events. The network may allocate resources by estimating
the rate of D2D transmission events. The network may allocate
resources by estimating the rate of transmission by WTRUs sharing
the resource. The network may allocate resources by targeting a
specific collision rate, for example, such that the network does
not over-allocate the resources (e.g., low collision rate,
sub-optimal use of resources, etc.) and/or under-allocate the
resources (e.g., high collision rate, lower efficiency of the
discovery mechanism, etc.).
The network may not determine the proper operating point when
allocating resources. For example, the network may not know the
frequency of transmission of the discovery signals (e.g., in case
of WTRU-autonomous triggers), the number of active transmitting
WTRUs (e.g., in case discovery transmission is supported in IDLE
mode), the geographical distribution of the WTRUs (e.g.,
transmitting or receiving) involved in D2D transmissions (e.g.,
discovery process(es) or data related transmissions, such as SA
and/or data) in a given cell for which resources are allocated,
and/or the like.
The network may redistribute the load and/or minimize collisions
risk. The network may monitor resource usage for a transmission(s)
(e.g., D2D transmission, discovery signal, data related
transmission, and/or the like) in shared resources, for example,
such that the network may re-allocate resources when high collision
rates are detected. When the network may determine that collisions
are below a certain threshold, the network may determine that the
outcome of the discovery process is a function of the proximity
between WTRUs, for example, given that interference may be deemed
to be at an acceptable level for the allocated resources.
The WTRU may identify one or more of the resources used for
transmission using indices. A reporting mechanism may include
resource usage. Resource usage may include information related to
past transmissions of a discovery signal for a given resource
allocation. For example, resource usage may include information
related to planned and/or scheduled transmission of a discovery
signal and/or transmissions of a discovery signal that happened in
a past configured time period. Reporting may be assembled by a
transmitting WTRU. Reporting may be received by a network node, for
example, a node from which the WTRU has received the configuration
for the resource allocation for transmission of discovery signals.
Reporting (e.g., which may include format, triggers, time windows,
and/or the like) may be configured, for example, together with the
resource allocation.
The network node (e.g., a base station such as an eNB) may
configure one or more transmitting WTRUs that are configured with
similar resource allocation for reporting. When the network node
receives one or more reports, the network node may use the received
information to derive collision probability for a resource. The
network node may determine whether or not such probability is above
a threshold. If above a certain threshold, the network may initiate
a reconfiguration for one or more WTRUs, for example, such that the
discovery signals are better spread across the allocated resources
in the cell.
WTRUs may be in proximity of each other but the interference levels
(e.g., which may be due to collisions within the resource used for
the discovery signal) may impair other WTRUs from properly
receiving the discovery signal. The WTRUs and/or the network may
determine whether another WTRU did not discover the WTRU, for
example, because the WTRU is not in proximity and/or because of the
collisions.
A D2D discovery may be a Type 1 D2D discovery where a WTRU may
select a resource. A D2D discovery may be a Type 2 discovery where
a network element may select a resource for a WTRU. A D2D
communication may be a Mode 1 D2D communication where a network
elements may control resource and/or transmission parameters for a
WTRU. Mode 1 D2D communication may be used when the WTRU is in
coverage. A D2D communication may be a Mode 2 D2D communication
where a WTRU may determine resources(s) and/or transmission
parameter(s). Type 1 D2D discovery may be similar to Mode 2 D2D
communication.
D2D communication transmission may take place under network
coverage or outside of network coverage. A WTRU may be configured
to operate without network control (e.g., in Mode 2 D2D
communication), for example, while WTRU communications under
network coverage may be controlled by a network base station and/or
an eNB (e.g., Mode 1). A WTRU may select resources for
transmissions autonomously when, for example, WTRU communications
take place outside of the network coverage. The network may be
unaware of potential high interference situations. The network may
be made aware of the D2D resources utilization, for example, so
that resources may be available for D2D communications.
Collisions of the SA and/or data may occur when outside of network
coverage. Collisions of the SA and/or data may occur between a WTRU
controlled by an eNB and another WTRU outside network coverage.
The network may re-use (e.g., allocate) the same resource to one or
more WTRUs when, for example, under network coverage. WTRUs may be
in proximity when a network may not be aware of the geographical
location of some WTRUs. The transmissions may collide on the same
resources.
The report may include one or more of the following. The report may
include the identity of resources (e.g. the concerned resources),
the identity of the discover process and/or event, location
information, the outcome of a discovery process and/or event, the
outcome of one or more transmission events, measured resource
utilization, whether network resource configuration may be
insufficient, a report by a monitoring WTRU on the outcome of
discovery signal decoding, and/or the like.
A concerned resource may refer to a resource used for transmissions
of direct WTRU-to-WTRU signals, for example, a discovery signal
transmission, SA, data pattern index, and/or the like. For example,
the report may include one or more indices describing one or more
of the resources (e.g., in time/frequency, for example subframe(s)
or PRB(s)), which may be used for transmission.
A reported resource may be associated with one or more of the
following. For example, a reported resource may indicate the
resource for which the WTRU has performed a transmission. For
example, the reported resource may indicate a resource for which
the WTRU has performed a transmission within a period, for example,
the last Z resource allocation period (e.g., a frame, a period
represented by Y TTIs, Y ms, and/or Y frames). The period may be
configurable. The report may be sent by a transmitting WTRU.
For example, a reported resource may indicate a resource for which
the WTRU may be expected to perform a transmission, for example, a
transmission that may not have been performed at the time the WTRU
assembles (e.g., generates) the report. For example, the reported
resource may indicate a resource for which the WTRU may be expected
to perform a transmission for a period, for example, the next Z
resource allocation period (e.g., a frame, a period represented by
Y TTIs, Y ms, and/or Y frames). The period may be configurable. The
report may be sent by a transmitting WTRU.
For example, a reported resource may indicate an index of a
resource for which the WTRU has measured the largest amount of
energy (e.g., one or more). For example, a reported resource may
indicate an index of a resource for which the WTRU has measured the
largest amount of energy within a period, for example, the last Z
resource allocation period (e.g., a frame, a period represented by
Y TTIs, Y ms, and/or Y frames). The period may be configurable. If
multiple resources are reported, the signaling format may include
means for the receiver to determine the number of elements in the
report, for example, by including the total number of elements in
the report. The report may be sent by a monitoring WTRU and/or by a
transmitting WTRU. For example, a reported resource may indicate an
index of a resource for which collision has been detected.
For example, a reported resource may indicate an index of the
resource or index of patterns for which a transmission failed
(e.g., no acknowledgment(s) where received or a percentage of the
transmissions were not acknowledged)
For example, a reported resource may indicate an index of a
resource for which a near-far effect has been detected.
For example, the WTRU may report an index corresponding to a set of
resources and/or a process identity (e.g., an entity receiving the
report may determine the concerned set of resources) followed by
zero (e.g., if no transmission has occurred for the reporting
period). The WTRU may report one or more indices each corresponding
to a resource in which the WTRU has performed a transmission and/or
is expected to have performed a transmission. A report may include
the identity of the discovery process and/or event. An identity may
be associated with a concerned resource and/or may identify (e.g.,
implicitly identify) a concerned resource. A monitoring WTRU may
report the ID of a transmitting WTRU with a discovery signal that
has been successfully decoded on a resource and/or a set of
resources (e.g., identification may correspond to the ProSe ID
decoded on the discovery resource). A WTRU may report the ID of one
or more transmitting WTRUs, for example, when near-far effect
causes issues (i.e. when received power is strong, when received
power is faint). A WTRU may report the ID carried on the SA of
interest. A WTRU may report the ID carried on the SA associated to
the D2D data transmission for which the WTRU is reporting.
A report may include location information. Location information may
be associated with a discovery signal transmission, a discovery
signal reception, and/or the report. A WTRU (e.g., a transmitting
WTRU and/or a receiving WTRU) may determine its location, for
example, based on the cell ID, GPS information, and/or other
location information. The WTRU may include the location information
in the report.
A report may include an outcome of a concerned discovery process
and/or event. If the WTRU has means to determine whether or not a
discovery process and/or event has been successful, the WTRU may
report the outcome for the concerned resource, discovery process,
and/or event. For example, a WTRU may determine that the outcome is
successful for a discovery process and/or event that may be
multidirectional. A multidirectional discovery process and/or event
may be from the reception and/or detection of a discovery signal
from another WTRU, for example, as a response to its own
transmission. A multidirectional discovery process and/or event may
be from the establishment of a direct communication channel with
one or more WTRUs subsequent to the transmission of the discovery
signal for the concerned resource(s) and/or for the concerned
discovery process and/or event.
A report may include the outcome of at least a transmission
attempt. A transmitting WTRU may report a failure to transmit a D2D
or discovery message (e.g., due to no and/or limited available
resources for a WTRU to transmit a discovery signal, for example,
for a defined period of time, and/or due to a collision on a
resource with another transmission.
A report may include the outcome based on resource availability.
The WTRU may determine that insufficient resources are available
for transmission (e.g., of discovery signal, SA or D2D data)
according to one or a combination of the following.
The WTRU may determine that insufficient resources are available
for transmission when the measured received energy on one or more
of the resources (e.g., all resources) are above a certain
threshold. Resources may be considered to be occupied by other
WTRUs.
The WTRU may determine that insufficient resources are available
for transmission when the WTRU determines other WTRUs are using one
or more of the resources (e.g., all resources), for example, which
may be determined by means of receiving announcement messages
(e.g., SA) and/or other messages indicating which resources are
being used. There may be no resource available for the WTRU to
transmit, for example, a discovery signal, SA or D2D data.
The WTRU may determine that insufficient resources are available
for transmission when the network is not allocating any resource
for a D2D WTRU, for example, within a time period.
The WTRU may determine that insufficient resources are available
for transmission. The WTRU may determine the number of resource
available is insufficient (e.g., for the WTRU to meet the required
and/or target discovery QoS, transmission rate, and/or D2D data)
for example, based on the received energy measured on the
resources, a certain threshold, and/or based on the received SA,
This may be determined, for example, for a period of time.
The transmitting WTRU may report after one or more successful
transmissions. A successful transmission may include the WTRU
finding available resource(s) to transmit a discovery signal. The
WTRU may report one or more of the following information associated
with a successful transmission.
The WTRU may report the number of transmission attempts before the
WTRU can successfully perform a transmission of, for example, a
discovery signal, D2D transmissions, D2D data, and/or SA (e.g., the
number of sub-frames in which no resources were available). A
transmission attempt may include one or more discovery subframes in
which the WTRU attempts to transmit a D2D transmission, for
example, over the air on an allowed discovery resource. For
example, the WTRU may determine that an attempt has failed if the
WTRU is allowed to transmit on the D2D resource(s) but does not
find an available resource (e.g., the measured energy on the
resource is above a threshold) for one or more subframes.
The WTRU may report the average time it takes to successfully
transmit a discovery signal, for example, which may be determined
to be the time it is available for transmission to the time it
takes to transmit it over the air. The average time may be
determined over a number of discovery signal transmissions, over a
number of discovery periods, and/or within a single period. The
WTRU may report the ratio of attempts to success. The WTRU may
report the amount of D2D data. The WTRU may report the number of
D2D data transmissions carried out by the WTRU (e.g., in terms of
MAC PDUs, total data delivered, data rate, etc.).
The transmitting WTRU may send the report after determining that it
has insufficient resources to meet its target QoS and/or discovery
transmission rate, for example, for a configured amount of time.
The WTRU may report resource availability, resource utilization,
and/or the amount of resources used by the WTRU to meet its target
QoS and/or discovery transmission rate, for example, as determined
per the WTRU discovery processes and/or D2D data configuration.
The report may include the outcome based on transmission
acknowledgement. A WTRU may have means to determine whether a
transmission or a plurality of transmissions within a time period
were successful by, for example, reception of acknowledgment of
transmitted PDU (e.g. HARQ, RLC, TCP/IP ACK, etc.). A WTRU may
determine that a PDU or a plurality of PDUs within a time period
were not delivered, for example, due to lack of acknowledgment for
those PDUs, or lack of a response from the receiving WTRU. For
example, a WTRU may consider a transmission successful if a PDU was
acknowledged. A WTRU may consider a transmission unsuccessful if,
for example, a PDU exceeds its retransmission attempts without
receiving an ACK. A WTRU may report failure to transmit on a given
resource, a plurality of configured resources for reporting, or a
resource plurality (e.g., a pattern) within a time. A WTRU may
report number of failures or successes over total transmission
opportunities/attempts in a time period. A WTRU may report
percentage of failures over transmission opportunities. A WTRU may
report success rate or failure rates on a resource. A WTRU may
report a plurality of configured resources for reporting. A WTRU
may report a resource plurality (e.g., pattern) measured within a
time. A WTRU may report an index of the resource, resource
plurality or pattern used for the transmission in which failure to
transmit may have been detected. A WTRU may report TTIs in which
failure may have been detected.
The report may include the measured resource utilization. The
transmitting and/or monitoring WTRU may report the measured
resource utilization while attempting to transmit and/or receive a
discovery signal, for example, over a period of time regardless of
whether it is attempting to transmit or not. The resources a WTRU
is measuring may be configured by the network. A WTRU may determine
the resources to measure based on, for example, the available
resources for D2D transmissions (e.g., discovery, SA, data and/or
data patterns). The report may include the average number of
occupied and/or available resources (e.g., discovery signal
resources, SA, D2D data pattern) per subframe over a defined period
(e.g., a discovery occasion, a D2D data scheduling interval) and/or
over a number of subframes. The report may include the total and/or
average number of occupied and/or available resources per subframe
(e.g., with an energy above and/or below a threshold, or based on
successfully detected SA, and/or based on successfully decoded
discovery signals). The report may include whether a pattern is
occupied or available. A pattern may be considered occupied if one
or more resources (and/or transmission opportunities) within the
pattern are considered occupied (e.g., based on energy level
measurements on those resources). A WTRU may report an occupied
pattern. A WTRU may report the number of occupied patterns over
available patterns. A WTRU may provide for a configured pattern to
report. For example, a WTRU may provide a configured pattern to
report on whether the pattern is occupied or not. The report may
include the minimum number of occupied and/or available resources
and/or subframe in which this minimum value occurred. The report
may include the number of subframes within a defined period, for
example, in which x resources or less where available (e.g., or y
resources or more where occupied), and/or where x and y are numbers
configured by the network.
The report may include a metric that may indicate a percentage, a
ratio or a number of resources that are occupied and/or available
in a subframe and/or a set of subframes, for example, within a
defined period. The report may include the metric during a period
of time (e.g., a D2D scheduling period). The report may include an
average of the number of resources or the actual number of
resources (e.g., or the percentage of resources) on subframe(s)
over a defined period (e.g., one subframe, a plurality of
subframes, and/or a discovery occasion) with a measured energy
level above a threshold, below a threshold and/or those resources
for which a signal (e.g., SA<discovery, D2D data) was
successfully detected. The threshold may be configured by the
network as part of the configuration message and/or may correspond
to the threshold used by the WTRU to determine whether a resource
is available for transmission or not.
The report may include the amount of energy the WTRU measured. The
amount of energy may be measured on a resource(s) and/or on a set
of resources over a subframe and/or a set of subframes. The WTRU
may report an index to a resource, a plurality of resources (e.g.,
a pattern), the measured energy level, and/or the subframe in which
the measurement was taken. The WTRU may report an index to a
resource and/or an average measured energy on the resource(s) over
a period time. The report may include the amount of energy on one
or more resources with the largest energy (e.g., largest X energy
amounts).
The report may indicate that the network resource configuration may
be insufficient. The transmitting WTRU may be configured to report
that the amount of resources currently allocated by the network
(e.g., in the current cell) are insufficient for the WTRU to meet
the QoS and/or transmission rate of the WTRU discovery process or
D2D data transmission. The WTRU may report after a new
configuration is received (e.g., from the SIBs) and/or after the
WTRU has changed cell (e.g., in Idle mode) and the amount of
resources allocated in the new cell are insufficient for the WTRU.
The WTRU may report to the network the amount of resources required
for the WTRU to meet its target QoS and/or discovery transmission
rate, for example, as determined per the WTRU discovery processes
configuration or D2D data transmission configuration.
The report may include a report by a monitoring WTRU on the outcome
of discovery signal or D2D transmission decoding. For example, the
monitoring WTRU may report a number and/or rate of failures and/or
successes on a dedicated resource, a plurality of resources, or a
received data pattern (e.g., for type 2 discovery, mode 1
communications, or type 2 discovery) (e.g., the rate of successful
reception over one or more scheduled occasions. The report may
indicate a decoding failure, which for example, may refer to when
the monitoring WTRU fails to decode the discovery signal or D2D
transmission on a resource. The report may indicate a decoding
success, which for example, may refer to when the monitoring WTRU
successfully decodes the discovery signal on a resource. The report
may indicate a decoding failure or decoding success for one or more
(e.g., a plurality of) resources. A WTRU may attempt decoding D2D
transmissions on a particular resource set within a scheduling
period (e.g., WTRU decoded the SA indicating transmission
opportunities for the WTRU). A WTRU may count the number of
successful or failed decoding attempts. A WTRU may count the number
of successful or failed HARQ processes. A report may include
decoding failure for a plurality of resources (e.g., X out of Y
HARQ processes have failed or a percentage of the detected failures
over total reception opportunities within a scheduling period have
been observed). The report may indicate the rate of a decoding
failure and/or success, which for example, may refer to the ratio
between the number of failures and/or successes on a resource
and/or a total number of decoding. The number may be the total
number of failures on each resource, the average number of failures
over all resources in a subframe, and/or the average number of
failures on a single resource over a number of subframes.
The report may indicate the number of resources on a subframe
(e.g., or average thereof) in which the WTRU detected the presence
of a discovery signal or data transmission but failed to
successfully decode the signal. The WTRU may consider that it
detected the presence of a discovery signal when one or more of the
following occurs: the received total energy measured over the
resource is above a threshold and/or the received level of a
reference signal measured over the resource (e.g., a correlator
implementation) is above a threshold. The reference signal may be a
signal of known properties.
The WTRU may determine a failure to decode based on a cyclic
redundancy check (CRC) transmitted, for example, along with the
remaining payload of the discovery signal. The CRC may be masked
with a RNTI known by the receiving WTRU, for example, within a
period The period may be configurable. The period may be the last Z
resource allocation period (e.g., a frame, a period represented by
Y TTIs, Y ms, and/or Y frames, and/or the like). The WTRU may
determine a success to decode a signal based on successfully
receiving and/or verifying a CRC.
The report may indicate the number of resources in which a
discovery signal was received on a subframe and/or a number of
subframes. The report may indicate the number of failed decoding
attempts and/or number of subframes in which a discovery signal was
successfully decoded and/or passed to higher layers.
The report may indicate an index of the resource(s) on which the
monitoring WTRU fails to decode the discovery signal(s), for
example, within a period. The period may be configurable. The
period may be the last Z resource allocation period (e.g., a frame,
a period represented by Y TTIs, Y ms, and/or Y frames, and/or the
like). The report may be sent by a monitoring WTRU. The report may
include a number of successfully decoded SA transmissions in a time
interval. The report may include the number of successfully decoded
SA transmissions for the associated data transmission, for example,
as determined by the identifier in the SA or via the higher layers
(e.g., MAC header, ProSE Identifier, etc.). The report may include
the identity associated with an SA that may be determined to cause
issues, such as interference/near-far effect. The report may
include the identity associated to an SA for which SA detection may
be successful but data reception may fail (e.g., for a duration of
time).
The report may include an interference level that measured by the
WTRU. The WTRU may be configured perform a noise measurement, for
example at a noise measurement occasion. For example, the network
may not schedule a D2D or cellular communication during one or more
subframes and the WTRU may perform the noise measurement during the
unscheduled subframe(s). The WTRU may take noise measurement
periodically, for example at one or more interference measurements
occasions. The WTRU may be configured to measure the level of
interference over the set of allocated D2D resources (e.g.,
discovery time/frequency resources). The WTRU may be configured to
report the level of interference above the noise level based on a
measurement. The WTRU may be configured to report when the
measurement is above or below a configured threshold.
The report may be bound in size, for example, such that at most a
number of elements are included in the report and/or a maximum
number of reference period(s) may be reported.
There may be one or more triggers for the WTRU to create (e.g.,
generate) and/or send (e.g., transmit) the report. For example, the
WTRU may initiate the creation and/or transmission of a report when
it receives L3 signaling that requests a report. The WTRU may
initiate the transmission of a report when the WTRU is configured
for reporting and another trigger initiates transmission of the
report. The signaling may be specific to a discovery process and/or
event (e.g., associated to a single identity), to a subset of
discovery processes and/or events (e.g., associated with one or
more identities and/or per type of resource allocation), and/or may
be WTRU-specific (e.g., applicable to one or more identities). For
example, the WTRU may initiate the transmission of a report if
there is at least one or more transmissions applicable for the
reporting period. The WTRU may transmit the reports alone and/or as
part of a message reporting successful decoding of a discovery
signal of interest, for example, to the ProSE server. The ProSE
server may forward the report to the RAN and/or provide information
(e.g., load/configuration information) to the RAN, the MME, eNB,
etc.
The WTRU may initiate the creation and/or transmission of a report
periodically, for example, if there is at least one or more
transmissions applicable for the reporting period. For example, the
reporting may be periodic at the end of a discovery occasion and/or
after a number of discovery occasions. A WTRU may be configured to
report periodically in D2D communications, for example, along a
periodical BSR.
The WTRU may initiate the creation and/or transmission of a report
in an aperiodic manner. The WTRU may initiate the transmission of a
report via the reception of control signaling that requests that
the WTRU perform the reporting. The signaling may be received from
a network node. The signaling may be dedicated signaling and/or
signaling applicable to a plurality of WTRUs (e.g., received on a
broadcasting channel and/or on a common control channel). For
example, signaling may be carried along with a grant transmitted by
an eNB. The WTRU may initiate the transmission of a report in an
aperiodic manner, for example, if there is at least one or more
transmissions (e.g., configurable transmissions) applicable for the
reporting period.
The signaling may indicate one or more WTRUs (e.g., using a common
identity, such as scrambling of a request using a common RNTI
and/or a request sent on a common control channel). The signaling
may indicate one or more WTRUs configured with at least one
resource allocation (e.g., a WTRU configured for discovery and/or
for direct WTRU-to-WTRU communications). The signaling may indicate
the resource allocation for which the reporting is applicable. For
example, the control signaling may include resource allocation
information and/or indexing, for example, such that a WTRU may
determine whether or not it corresponds to one or more of its
resource configurations. If the WTRU determines that the resource
allocation information and/or indexing correspond to one or more of
its resource configurations, the WTRU may initiate the reporting
for the resource. The signaling may indicate the identity of the
process and/or event. For example, the control signaling may
include an identity, for example, such that a WTRU may determine
whether or not it corresponds to one or more of its processes. If
the WTRU determines that the identity of the process and/or event
corresponds to one or more of its processes, the WTRU may initiate
the reporting for the resources associated to the process and/or
event. The WTRU may initiate the creation and/or transmission of a
report based on a change of operation status. For example, the
report may be triggered after the last subframe of the discovery
period and/or occasion. The WTRU may report to the network when it
resumes normal operation with the eNB. The report may be triggered
after a scheduling period is completed. For example, a WTRU may
transmit a report after a configurable number of scheduling
periods.
The WTRU may initiate the creation and/or transmission of a report
based on an outcome of a discovery or data transmission process
and/or event. For example, the WTRU may initiate reporting when it
determines that the discovery or transmission of data is not
successful. For example, the WTRU may initiate reporting when the
WTRU has determined that the discovery or data transmission has not
been successful for a certain period of time and/or for a certain
number of attempts (e.g., a period with at least one transmission
of a discovery signal), which may be configurable aspects of the
reporting.
The WTRU may initiate the creation and/or transmission of a report
based on an outcome of SA reception/transmission. A WTRU may
initiate reporting when it determines that reception of a
configurable number of SA is not successful. A WTRU may initiate
reporting when it determines that it may not have transmitted the
SA a configurable number of times, for example, when no SA resource
is available.
The WTRU may initiate the creation and/or transmission of a report
based on an outcome of the physical layer discovery signal decoding
by a monitoring WTRU. For example, the WTRU may initiate a report
to the network when it determines that a certain rate of decoding
failures and/or successes has been reached. For example, the report
may be triggered when the WTRU detects that a certain number of
decoding failures have occurred in one or more allowed discovery
subframes or D2D communications subframe (e.g., as defined by
transmission pattern).
The report may be triggered when the WTRU detects a failure trigger
by a monitoring WTRU. A report may be triggered when the WTRU fails
to decode a configured number of discovery signals or data
reception opportunities on one or more resources, for example on a
subframe and/or over a number of subframes (e.g., consecutive
subframes, a number of subframes over a configured period, as
indicated by a data pattern, and/or the like). A report may be
triggered when the rate of decoding failures of D2D transmission
(e.g., a discovery signal or D2D data) is above a threshold on a
subframe and/or a number of subframes (e.g., consecutive subframes,
a number of subframes over a configured period, and/or the like).
The rate of decoding failure may be determined to be the number of
failed decoding attempts over the number of total decoding attempts
on resources in which a discovery signal is being transmitted. The
rate of decoding failure may be determined to be the number of
failed decoding attempts over the total number of monitoring
resources. A report may be triggered when a WTRU determines the
rate of failure of SA or D2D data communications (e.g., in terms of
block error rate, BER, outage, etc.) during a period of time. A
report may be triggered when a WTRU reports to the network when the
rate of failure is larger than a threshold.
A report may be triggered based on the success of packets decoded
(e.g., the number of successfully decoded packets over the total
number of attempts).
A report may be triggered based on an outcome of a transmission
attempt by a transmitting WTRU. For example, the WTRU may initiate
the transmission of a report based on the outcome of a transmission
attempt (e.g., failure to transmit, the number of attempts before a
successful transmission, and/or the like). A failure to transmit
may refer to the WTRU not finding an available resource for
transmission on a discovery resource (e.g., an allowed discovery
resource) in one or more discovery subframes (e.g., allowed
discovery subframes). An attempt to transmit may include the WTRU
trying to transmit a discovery signal over one or more allowed
resources, for example, on a discovery subframe. A successful
transmission may include the WTRU finding an available resource for
transmission and/or transmitting the discovery signal over the air.
For example, attempt to transmit may refer to a WTRU trying to
transmit an SA and/or the associated D2D data, such as for D2D data
communications. A successful transmission may refer to a WTRU
finding available resources for transmission of the SA and the
associated D2D data, such as in D2D data communications.
The WTRU may initiate the creation and/or transmission of a report
based on a failure to transmit. For example, the WTRU may initiate
the creation and/or transmission of a report as a result of
failures to transmit at least a discovery signal in a set of
available discovery resources (e.g., resource pool). The failure to
transmit may be when the WTRU fails to transmit in a given
sub-frame or a set of sub-frames. The failure to transmit may be
when the WTRU fails to transmit the discovery signal within a
discovery occasion. The failure to transmit may be when the WTRU
fails to find a resource for transmission over a configured period
of time. The failure to transmit may be when a WTRU fails to
transmit an SA and/or associated data within a period (e.g., the
period for which a network grant may be valid). The failure to
transmit may be when a WTRU fails to find a resource for
transmission of an SA and/or associated data within a period (e.g.,
the period for which a network grant is valid). The failure to
transmit may be when the WTRU detects that it failed to transmit a
configured number of times during a period of time T. For example,
the failure count over a period of time may be related to multiple
transmissions of discovery signals within a discovery occasion
and/or multiple discovery occasions, or for D2D data communications
to one or more PDCP, MAC or RLC PDUs (e.g., the WTRU may have X
failures among Y discovery subframes within a discovery period, a
WTRU may have X MAC PDU failures among Y new data transmission
occasions within a scheduling period). The failure to transmit may
be when the WTRU detects that the number of failures for a
discovery signal transmission attempt is above a threshold within a
configured period of time (e.g., if for each attempt to transmit a
discovery signal the WTRU fails to transmit for a period of time).
The failure to transmit may be when the WTRU fails to transmit over
a configured number of consecutive allowed discovery subframes. The
failure to transmit may be when the WTRU fails to find sufficient
resources for transmission to achieve the target QoS and/or
discovery transmission rate over a configured period of time.
The WTRU may initiate the creation and/or transmission of a report
based on a number of attempts before a successful transmission. For
example, the WTRU may report to the network based on the number of
attempts before the WTRU successfully transmits one or more a
discovery signals or D2D data communications signals. The report
may be triggered when the WTRU has more than X tries before a
success for a given transmission and/or a number of transmissions.
The report may be triggered when the average time before success
for a given WTRU is larger than a threshold. The report may be
triggered when the success rate (e.g., the number of successes/the
total number of tries) is lower than a threshold.
The WTRU may initiate the creation and/or transmission of a report
based on a measured resource utilization. For example, the WTRU may
initiate a report based on a measured resource utilization status.
The report and resource utilization may be measured by a
transmitting WTRU and/or a monitoring WTRU. A discovery measured
resource utilization may refer to a WTRU performing a measurement
on a discovery resource in one or more subframes and/or measuring
the energy level on the resource.
A trigger related to resource utilization may be when the number of
resources (NR) with measured energy below a threshold in a subframe
is below a configured threshold, for example, over a period of
time. The period of time may be, for example, a subframe, a
configured number of subframes, a number of consecutive subframes,
a percentage of allowed discovery subframes within a discovery
occasion, and/or the like. A trigger related to resource
utilization may be when the number of resources (NR) with measured
energy above a threshold in a subframe is above a configured
threshold over a period of time.
A trigger related to resource utilization may be when the average
measured energy over all or a subset of discovery resources in
subframe is above or below a threshold, for example, for a period
of time. A trigger related to resource utilization may be when the
ratio of resources with measured energy below or above a threshold
over the total number of discovery resources in a subframe is below
or above a threshold, for example, over a period of time.
A trigger related to resource utilization may be when the WTRU
determines that the resource utilization over a configured period
of time (e.g., based on the ratio and/or number of resources with
measured energy below or above a threshold) is insufficient for the
WTRU to meet the target QoS and/or discovery transmission rate.
The WTRU may initiate the creation and/or transmission of a report
based on a measured resource utilization in, for example, D2D
communications. For example, a WTRU may initiate a report based on
a measured resource utilization status, for example, in D2D
communications. The report and resource utilization may be measured
by a transmitting WTRU and/or a monitoring WTRU.
A trigger related to resource utilization may be when the number of
SA resources successfully decoded is above a configured
threshold.
A trigger related to resource utilization may be when the number of
SA resources successfully decoded is below a configured
threshold.
A trigger related to resource utilization may be when the number of
D2D data PRB (e.g., as indicated by the aggregated received SAs) is
above a configured threshold.
A trigger related to resource utilization may be when the number of
D2D data PRB (e.g., as indicated by the aggregated received SAs) is
below a configured threshold.
A trigger related to resource utilization may be when the energy
measured in a configured plurality of PRBs (e.g., associated to D2D
data communications) is above a threshold.
A trigger related to resource utilization may be when the energy
measured in a configured plurality of PRBs (e.g., associated to D2D
data communications) is below a threshold.
A trigger related to resource utilization may be when a WTRU
determines that the resource available may be insufficient to meet
the target and/or required QoS for a D2D data transmission service
(e.g., VoIP, video streaming, etc).
A WTRU may be configured to trigger transmission of a report upon
detection of a change in coverage situation and/or D2D transmission
mode (e.g., Mode 1 (eNB controlled), Mode 2 (non-eNB controlled)).
A WTRU may be configured to trigger transmission of a report. A
WTRU may be configured to trigger transmission of a report when a
WTRU enters eNB coverage. For example, a WTRU may detect that it
has uplink coverage when a WTRU successfully connects to the eNB
(e.g., RRC connected state).
A WTRU may be configured to trigger transmission of a report when a
WTRU enters Mode 1. A WTRU may be configured to transmit a report
when a WTRU is configured to operate in Mode 1.
A WTRU may be configured to trigger transmission of a report when a
WTRU changes cells. A WTRU may be configured to transmit a report
to a new eNB, for example, after a handover. A WTRU may be
configured to transmit upon transmission of a tracking area update.
A WTRU may be configured to transmit when a WTRU is configured with
D2D data communications and changes cell, for example, in Idle
mode.
The WTRU may transmit a report using L2 (e.g., MAC) signaling
(e.g., as a MAC Control Element), as L3 (e.g., RRC) signaling
(e.g., as a RRC PDU, for example, as part of a reporting
procedure), and/or as higher layer signaling (e.g., NAS signaling,
application signaling, and/or the like). For example, the WTRU may
receive control signaling on the PDCCH (e.g., an aperiodic request)
that triggers reporting. The WTRU may assemble the report as a MAC
control element and include it in an uplink transmission (e.g., the
next uplink transmission). The eNB may be the endpoint of the
reporting procedure.
The WTRU may receive a request on a signaling radio bearer (SRB) as
an RRC PDU that triggers reporting. For example, the WTRU may
assemble the report as a RRC PDU and make it available for
transmission on the SRB.
The WTRU may trigger reporting at the application level. For
example, the WTRU may assemble an application layer control packet
and make it available for transmission as a RRC PDU (e.g., and make
it available for transmission on the concerned SRB (e.g. in case
NAS is used)) and/or as a user plane data (e.g., and make it
available for transmission for a corresponding DRB). The ProSe
and/or the application server may be the endpoint of the reporting
procedure.
The WTRU may trigger reporting if the WTRU is in RRC IDLE mode. For
example, the WTRU may initiate a transition to CONNECTED mode and
transmit the report according to the applicable signaling method.
The WTRU may remain in IDLE mode and delay the transmission of the
report until it moves to CONNECTED mode, for example, if RRC and/or
a higher layer protocol is used.
A network node (e.g., a base station, for example an evolved Node B
(eNB)) may receive the report. The network node that receives the
report may determine the blocking rate for a given resource, for
example, if the report is received from multiple sources. The
network node that receives the report may initiate a procedure that
reconfigures the resources for one or more WTRUs such that the
estimated rate may be lower, for example, if the rate is above a
certain threshold.
Discovery signal transmission control for resource management may
be provided. A network entity (e.g., an eNB, a ProSe server, and/or
the like) may have direct control over the transmission of
discovery signals, for example, for the purpose of managing
resources allocated to D2D.
A WTRU may suspend and/or resume transmission of a discovery signal
in one or more resources following the reception of signaling from
the network. The network may utilize this functionality, for
example, to assess the level of interference and/or the load
generated by one or more WTRUs and/or to diagnose and/or
temporarily relieve a congestion situation in a resource. For
example, the network may determine that a WTRU may cause excessive
collisions and/or interference to other WTRUs in a resource by
suspending transmissions from the WTRU and/or receiving reports
from one or more other WTRUs that indicate improved performance
after the suspension. The network may take corrective actions, for
example, re-assigning the WTRU to a different set of resources,
restricting the WTRU to use a resource within a specific set of
resources (e.g., a resource from a particular resource pool),
increasing the amount of resources available for discovery signal
transmissions, and/or the like. When the WTRU receives signaling
indicating suspension of transmission, the suspension may remain
effective for a certain duration (e.g., until expiration of a timer
started upon reception of the signaling) and/or until reception of
signaling indication resumption of transmission. The duration of
the timer may be configured by higher layers and/or may be
indicated in the signaling.
The suspension and/or resumption of transmission may apply to one
or more discovery signals that are transmitted by the WTRU. The
suspension may be applicable to one or more (e.g., a subset of)
resources. The discovery signal(s) and/or resources may be
indicated in the signaling.
A WTRU may initiate transmission of one or more discovery signals
in one or more resources following the reception of signaling from
the network. The transmission may take place even if the WTRU would
not have otherwise triggered transmission of a discovery signal,
for example, based on an application and/or based on a
configuration from a ProSe server. The network may utilize this
functionality, for example, to control the load from discovery
signal transmissions over a period of time where other WTRU's are
configured to measure and/or report over a resource, for example,
according to examples provided herein. This may allow the network
to obtain information on a potential collision and/or interference
issue between WTRUs more reliably and/or quickly than
otherwise.
When the WTRU receives a transmission order (e.g., as per the
above), a property of the discovery signal may be set to a specific
value. The property may include the resource used for the
transmission of the discovery signal, the discovery payload, an
RNTI used to mask a CRC used for decoding the discovery signal, a
value and/or configuration of the demodulation RS, and/or the
like
A value of a property may be configured by higher layers, be
pre-determined, and/or be indicated in the signaling. A receiving
WTRU may determine that a received discovery signal that has a
property set to a specific value was transmitted for control and/or
management purposes (e.g., only for control and/or management
purposes). The receiving WTRU may determine that the received
discovery signal may not include useful information to be passed to
higher layers (e.g., except for reporting performance).
A WTRU that measures and/or reports over a resource may monitor one
or more discovery signals that match the at least one property. The
WTRU may transmit (e.g., periodically transmit) a discovery signal
according to the above properties without receiving a signaling
order. The transmission instances and/or property values may be
configured by higher layers.
Signaling mechanisms in support of discovery transmission control
may be provided. The signaling may be received at the physical
layer, at the MAC and/or RRC sublayers, and/or at higher layers.
For example, a WTRU may monitor downlink control information in a
search space (e.g., the common search space) using an RNTI. The
RNTI may be common to one or more WTRUs configured to transmit
discovery signals.
The signaling may include a paging message, for example, received
at the WTRU's paging occasion and/or at a paging occasion used for
the purpose of discovery transmission control.
The signaling may include an indication (e.g., explicit indication)
of the identity and/or set of identities of the WTRU and/or
discovery signal(s) related to the command. A set of identities may
be indicated with a group identifier. The mapping between a group
identifier and a set of identities may be configured by higher
layers (e.g., a WTRU transmitting a discovery signal may be
configured with a group identities, for example, for the purpose of
transmission control) and/or may include of a subset of bits (e.g.,
least or most significant bits) of the WTRU and/or discovery signal
identity.
A WTRU may determine to act on the received signaling
probabilistically. For example, the WTRU may draw a random number
(e.g., between 0 and 1) and determine that it is concerned by the
received signaling if the randomly picked number is below (e.g., or
is above) a threshold. The threshold may be pre-determined,
indicated in the signaling, and/or pre-configured by higher layers.
The use of a threshold may allow the network to control the
percentage of WTRUs and/or the percentage of discovery signals
concerned by an order to initiate and/or suspend transmission.
A single signaling order may be interpreted as a suspension order
by one or more WTRUs and/or as a transmission order by other WTRUs.
For example, a WTRU receiving signaling may determine that it may
initiate transmission of a discovery signal if its identity is
included in a first signaled group identity. The WTRU receiving
signaling may determine that it may suspend transmission of
discovery signal(s) if it is not included in the first group
identity and/or if it is included in a second group identity
included in the signaling.
The signaling for controlling transmission for a first subset of
WTRUs and/or discovery signal identities may be combined with
signaling used for triggering the measurement and/or reporting over
a discovery resource for a second subset of WTRUs and/or discovery
signal identities.
Mechanisms to allow WTRUs to coordinate resource usage may be
provided. Once a WTRU is configured with resources for transmission
of a discovery signal, the WTRU may perform transmissions
accordingly. If the WTRU is in-coverage with an eNB, the resource
pool and/or dedicated resources may be preconfigured and/or
dynamically configured by the network. If the WTRU is
out-of-coverage of an eNB, the WTRU may obtain resource
configuration from a stored pre-configuration and/or from a
coordinating entity (e.g., cluster-head). The resources used by the
transmitting and receiving entities may be coordinated, for
example, if discovery/communication is supported when WTRUs in the
coverage of the same configuring entity and/or associated with
configuration entities that coordinate with each other. Issues may
arise when a WTRU performs transmission and/or reception in
multiple domains at the same time, for example, if the
discovery/communication is supported in scenarios which are not
coordinated.
For resource allocation, the WTRUs may be pre-configured with a
resource pool to transmit/receive when operating in out-of-coverage
mode. In particular, all WTRUs may be also preconfigured with
resources to transmit and receive the resource configuration
information (e.g. where to send control information message e.g.
synchronization message). The WTRU may also be configured by a
controlling entity what resources to use within a resource
pool.
FIG. 6 is a diagram illustrating an example of scenarios for
in-coverage, out-of-coverage, and partial coverage D2D discovery
and/or communications.
The in-coverage WTRU may discover and/or be discovered by
neighboring WTRUs that may be controlled by other uncoordinated
controlling entities and/or may be operating in a different
spectrum. Since the eNB may provide resource pools for in-coverage
discovery, the WTRU may not be able to discover and/or be
discovered by the neighboring WTRU, for example, if the neighboring
WTRU is not monitoring the same resource pool. The in-coverage WTRU
may move (e.g., autonomously move) to a public safety (PS) spectrum
and/or out-of-coverage spectrum to perform reception and/or
transmission, however, for example, without network coordination
this may result in loss of data and/or loss of paging reception.
Mechanisms to allow coordination between the eNB and the
in-coverage WTRUs may be provided.
An in-coverage WTRU may determine to perform communication with an
out of coverage WTRU, act as WTRU-to-Network relay with another
WTRU, and/or determine to perform communication with a neighboring
WTRU that may determine the set of resources to use by a
pre-configuration and/or by a controlling entity (e.g., a cluster
head) which may not be coordinated with the serving eNB. The
resources and/or time used for transmission by a neighboring WTRU
may correspond to subframes in which the in-coverage WTRU may be
performing normal cellular communications. The in-coverage WTRU may
coordinate with the eNB to request time and/or resources in which
it can communicate with the neighboring WTRU without negatively
impacting the cellular connection with the eNB.
The WTRU may switch (e.g., autonomously switch) to transmitting
and/or receiving on the resources in which the neighboring WTRU is
expecting to receive and/or transmit. This may result in data loss,
the WTRU not transmitting in the UL, and/or missing paging
occasions while in idle mode. In order to avoid data losses and/or
loss of paging, coordination between the eNB, the in-coverage WTRU,
the out-of coverage WTRU, and/or the controlling entity out-of
coverage WTRU may be provided, for example, for the WTRUs using a
single transmit and/or receive. The coordination may involve
coordination of time patterns in which this communication is
expected to happen and/or a coordination of resources (e.g.,
frequency and/or time) in which this communication and/or discovery
may take place.
The coordination may aim at allowing controlling entities to align
the resources that the WTRUs involved in the communication are
using and/or to be aware of scheduling restrictions during these
time periods.
The network and/or coordinating entity may be made aware of
resource allocation conflicts, for example, such that the network
may re-allocate resources and/or schedule the WTRUs accordingly.
For example, this may be performed for communication across
different clusters that may be controlled by different entities.
The eNB may refer to a cluster head and/or controlling entity in a
group and/or cluster. The in-coverage WTRU may refer to a WTRU that
is connected to the cluster head and/or controlling entity. A
neighboring WTRU, PS WTRU, and/or out-of-coverage WTRU may refer to
a WTRU that is configured to operate in direct communication. The
resource pool and/or configuration for the neighboring WTRU, PS
WTRU, and/or out-of-coverage WTRU may be controlled by an
uncoordinated controlling entity different from the in-coverage
WTRU and/or for which the resources are pre-configured.
The methods described herein relating to in-coverage and
out-of-coverage may be applicable to allow coordination between a
WTRU that may be controlled by different uncoordinated controlling
entities or eNBs, etc.
An in-coverage WTRU may coordinate, request a gap(s), and/or
request resources to communicate with an out-of-coverage WTRU. FIG.
7 is a diagram of an example scenario of communication between an
in-coverage WTRU and an out-of-coverage WTRU. Interactions between
an in-coverage WTRU and an out-of-coverage WTRU, for example, to
negotiate resource allocation for the out-of-network link (e.g.,
PC5) may be provided. Interaction between the in-coverage WTRU and
an eNB, for example, to support resource reconfiguration and/or
gap/pattern configuration may be provided. The examples described
herein may apply to the case where an in-coverage WTRU performs
direct public safety communication on public safety resources.
Methods to negotiate resource allocation for out-of-coverage link
may be provided. The in-coverage WTRU may have a coordinated time
and/or gap pattern, for example, such that it may tune out of the
cellular link without the risk of losing data. The out-of-coverage
WTRU may be aware of when and/or where to expect to receive and/or
transmit, for example, to ensure that interested parties may
receive the communication.
A pattern for communication may refer to a time pattern (e.g., a
period, a cycle, a duration, and/or the like) in which the WTRU may
transmit and/or receive. A pattern for communication may refer to a
time pattern for reception and a time pattern for transmission. A
pattern for communication may include resource information, for
example, such a frequency, subframe(s), PRB(s), and/or the
like.
An out-of-coverage WTRU may determine and/or drive resource
allocation. FIG. 8 is a diagram of an example of signaling that may
be used for an out-of-coverage WTRU to determine and/or drive
resource allocation. Resource allocation may refer to a time, a gap
pattern, and/or a time and/or frequency configuration for the PS
link. For example, the out-of-coverage WTRU may provide and/or
broadcast (e.g., in a known pre-configured resource) the resource
allocation configuration it is configured to use and/or is using
for communication. Resource allocation may be in the form of an SA,
a broadcast synchronization message, a control message, and/or the
like. The resource configuration may include the time and/or
frequency pattern in which the PS WTRU is expecting to transmit
and/or receive.
The WTRU may provide a resource configuration if it determines that
an in-coverage WTRU is present. The WTRU may provide the resource
configuration periodically or all of the time and/or prior to data
transmission. The WTRU may provide the resource configuration when
WTRUs operating in different spectrums are expected.
A WTRU (e.g., an in-coverage WTRU) may receive (e.g., from an
out-of-coverage WTRU) a configuration and/or a time pattern. The
WTRU may communicate the configuration information in a report to
the eNB. The information communicated to the eNB may include a
recommended gap pattern and/or frequency resources for the
out-of-coverage WTRU, for example, for the out-of-coverage WTRU to
use to communicate. The in-coverage WTRU may determine to send this
information to the eNB, for example, if it determines that the
out-of-coverage WTRU is a WTRU belonging to the same group as in
the in-coverage WTRU (e.g., the WTRU is allowed to receive from
this device). The eNB may reconfigure the resource pool it uses
(e.g., for discovery and/or communication) and/or provide the
in-coverage WTRU with gaps and/or scheduling opportunities to
listen to the out-of-coverage link, for example, according to the
resources provided by the out-of-coverage WTRU. The eNB may provide
the gap pattern. The eNB may approve the use of the suggested gap
pattern.
The gap pattern may be translated and/or adjusted according to the
timing used by the controlling entity, for example, in the case
where the timing and/or reference frame numbers used to determine
the scheduling opportunities are different between an in-coverage
WTRU and a neighboring WTRU.
Resource allocation may be determined and/or driven by the eNB
and/or the in-coverage WTRU. FIG. 9 is a diagram of an example of
signaling that may be used for an eNB and/or an in-coverage WTRU to
determine and/or drive resource allocation. The resource usage
allocation for an out-of-coverage link may be driven by the
in-coverage WTRU and/or the eNB. For example, the out-of-coverage
WTRU may transmit (e.g., broadcast) a resource allocation pool that
it may use to select resources for operation and/or the in-coverage
WTRU may be aware of the resource pool according to the
pre-configured information. The in-coverage WTRU, for example once
it detects an out-of-coverage WTRU, may determine the resource pool
the neighboring WTRU is using. The in-coverage WTRU may not receive
this information from the out-of-coverage WTRU and/or it may rely
on the preconfigured resource pool for the PS it has. The network
may be aware of the resource pool pre-configured for the PS
WTRUs.
The WTRU (e.g., in-coverage WTRU) may send a report to the eNB, for
example, based on one or a combination of the triggers described
herein (e.g., upon detection of the need to communicate to as a PS
WTRU and/or communicate to a neighboring WTRU). The content of the
report may be described herein, for example, the report may include
the resource pool that the PS WTRU may be using, recommended time
pattern, pre-configured time pattern, etc.
The eNB, for example upon reception of this request, may determine
the scheduling opportunities and/or gaps to allocate to the
in-coverage WTRU for PS communication and/or discovery and/or may
send the gap pattern and/or time pattern and/or resource
configuration to the WTRU or approves the use of the requested time
pattern.
In the case of idle mode operation, the in-coverage WTRU, for
example, based on the discovery resource pool allocated for
in-coverage (e.g., time pattern and/or frequency) and/or the paging
occasions, may determine a time pattern that may allow the
in-coverage WTRU to tune out of the serving eNB and successfully
perform communication with the neighboring WTRU.
The in-coverage WTRU may be configured by the eNB with a reception
time pattern for communication with other WTRUs (e.g., in-coverage
and/or out-of-coverage to the eNB) and/or the in coverage WTRU may
have the pattern pre-configured.
The in-coverage WTRU, for example based on the determined pattern
(e.g., from the eNB and/or determined internally), may send a
message and/or report to the neighboring WTRU. The message may be
transmitted as a broadcast message, as a synchronization message,
and/or as a dedicated message to the WTRU and/or by using a control
message that may be received by WTRUs belonging to the same group.
The message and/or report may indicate the resource allocation,
time pattern, and/or frequency in which the in-coverage WTRU may
transmit and/or receive. The neighboring WTRU may relay and/or
transmit (e.g., broadcast) the message and/or pattern to its
controlling entity, which for example, may approve and/or configure
the neighboring WTRU with the requested pattern and/or may send a
new suggested pattern.
The eNB, for example in addition to a gap pattern and/or time
pattern, may provide the WTRU with a specific resource
configuration (e.g., frequency and/or time, for example by
specifying subframe(s) and/or PRB(s)) that the out-of-coverage WTRU
may transmit and/or receive with in-coverage WTRU, where for
example, the frequency may correspond to the in-coverage resource
pool. The out-of-coverage WTRU may be a standalone unattached
out-of-coverage WTRU that may be trying to connect to the network
using the in-coverage WTRU as a WTRU-to-NW (network) relay. The
out-of-coverage WTRU may be communicating with other in-coverage
and/or out-of-coverage WTRUs.
Interactions between an in-coverage WTRU and an out-of-coverage
WTRU may be provided. When the WTRU begins to operate in the relay
and/or PS mode, the WTRU may send one or more D2D synchronization
signals (D2DSS) and/or a control message (e.g., synchronization
message). The WTRU may advertise that it is capable of operating as
a relay and/or PS node in the control message. A neighboring WTRU
operating in vicinity which is looking for a coordinating entity
may monitor (e.g., periodically monitor) for D2DSS control symbols
and/or may detect the WTRU (e.g., in coverage WTRU, out of coverage
WTRU, relay WTRU, and/or the like). The triggers for a WTRU to
begin operating as a relay node may be based on pre-configuration,
based on measurements, based on explicit trigger from the network
and/or from the ProSe server, and/or the like.
The in-coverage WTRU may send resource pool information, obtains
acknowledgements, send a report to the eNB, and/or the like. The
WTRU operating as a relay and/or triggered to operate as a PS node
may operate in an unsolicited mode. For example, the WTRU may
advertise itself as a relay and/or a PS node. The WTRU may send an
advertisement message with one or more ProSe parameters (e.g.,
ProSe WTRU id, security, ProSe group id, etc.) and/or the resource
pool it may be using for a link with the out-of-coverage WTRU
and/or other PS nodes. The WTRU may operate as a cluster-head
and/or append this information as a part of cluster configuration
message, for example, for the synchronization message. This may be
used by the WTRU to support open discovery. The control message may
carry resource configuration provided by the eNB.
The out-of-coverage WTRU may send a response accepting the
configuration parameters. The response message may indicate one or
more (e.g., a subset) of the resources in the pool that are
acceptable to the out-of-coverage WTRU. The relay and/or the PS
node WTRU may send a report to the eNB with this information, for
example, as described herein. The eNB may accept this
configuration. The eNB may configure gaps and/or reconfigure
resources for the relay WTRU and/or PS node to be able to operate
with the out-of-coverage WTRU and/or PS node using gaps.
Resources may be used for relaying a control message (e.g.,
synchronization message). A WTRU operating as a relay may request
for resources to relay the control message. The WTRU operating as a
relay may use semi-statically allocated resources signaled by the
eNB (e.g., using SIB signaling) to relay the control message. The
WTRU operating as a relay may use preconfigured resources to relay
the control message. The resources may be explicitly preconfigured
for a control message and/or the WTRU may select (e.g.,
autonomously select) resources from a resource pool to be used for
relaying the control message.
The out-of-coverage WTRU may request resource pool information,
obtain information, send a report to the eNB, and/or the like. The
remote and/or PS node WTRU may send a solicitation message
requesting any neighboring WTRUs that can operate in a relay and/or
PS mode. The WTRU may operate as a cluster-head. The WTRU may
include the resource pool it expects to use for transmission and/or
reception and/or is using in the cluster configuration message, for
example, for the synchronization message. A WTRU (e.g., with
capability to operate in relay and/or PS mode, and/or operating in
solicited mode) may detect this node and/or respond by declaring
itself as a relay and/or PS node. The response message may indicate
the parameters identifying itself as a ProSe node (e.g., ProSe WTRU
id, ProSe group id, etc.), security configuration, and/or the like.
The responding WTRU may request a different resource pool, for
example, based on capabilities and/or an existing gap pattern
configuration.
The relay and/or the PS node WTRU may send a report to the eNB with
this information (e.g., as described herein), for example, once the
resource negotiation is concluded. This mode may support targeted
discovery. The eNB may accept the configuration and/or configure
gaps and/or reconfigure resources for the relay WTRU and/or PS node
to be able to operate with the out-of-coverage WTRU and/or PS node
using gaps.
Methods to coordinate a communication from a coordinating WTRU may
be provided. The WTRU may send a report. The WTRU may identify one
or more (e.g., all) of the resources in the report. A reporting
mechanism, a WTRU, and/or a WTRU transmitting a message may be used
to allow coordination of time and/or resources used by WTRUs in
coverage of different cells and/or clusters controlled by
uncoordinated entities. Reporting may include resource allocation
for an out-of-coverage link to assist the controlling entity and/or
transmitting entity to determine scheduling opportunities and/or
resource allocation. Resource allocation information may include
information relayed, transmitted, broadcasted by neighboring WTRUs,
and/or available (e.g., configured or preconfigured) in the
in-coverage WTRU.
Reporting (e.g., which may include format, triggers, time windows,
and/or the like) may be configured by the network (e.g., by a
network node such as an eNB). The network node may configure one or
more WTRUs that are configured to operate in a certain D2D
communication mode. The reception of this report by the network may
trigger actions.
The report may be transmitted to a coordinating entity and/or may
be transmitted in the form of a broadcast message, as a part of a
synchronization message, as a dedicated message by the coordinating
(e.g., in-coverage) WTRU, and/or the like.
The report and/or the transmitted message triggered by a WTRU may
include resource configuration from neighboring WTRUs. For example,
the report may indicate the resource pool information obtained from
the neighboring entities (e.g., WTRUs, cluster heads and/or eNBs,
and/or out-of-coverage WTRUs).
The reported configuration may include the resource set intended
for D2D discovery (e.g., frequencies, bandwidth, subframe(s),
PRB(s), time, and/or the like), the resource set intended for D2D
communications (e.g., frequency, bandwidth, subframe(s), PRB(s),
time, and/or the like), and/or the identity of the coordinating
entity and/or of the WTRU providing configuration information
(e.g., cluster head id, eNB id and/or WTRU id, group ID, Prose ID,
and/or the like).
The report triggered by a WTRU may include resources (e.g., a
sub-set of resources) within a resource pool or the resource
pattern that the in-coverage WTRU requests from the eNB (e.g., or
may use as previously received from the eNB and/or already
configured in the WTRU), for example, such that it may communicate
with the out-of-coverage WTRU. For example, the report may include
a suggested and/or used time pattern (e.g., cycle, duration, etc.),
frequency, and/or the like. The report may indicate a controlling
entity that may be taken into account and/or grant to the reporting
WTRU. The suggested time pattern may be received from the
neighboring WTRU and/or determined (e.g., autonomously) by the
in-coverage WTRU based on information it has available. For
example, the report may include one or more indices describing the
resource(s) (e.g., in time and/or frequency) within a resource pool
which the out-of-coverage WTRU and in-coverage WTRU have negotiated
and/or preconfigured to use for the out-of-network link.
The report triggered by a WTRU may include location information.
Location information may be associated with the reporting WTRU
and/or may be associated to the report. A WTRU (e.g., transmitting
and/or receiving) may determine its location, for example, based on
the cell ID, GPS information, and/or other location information,
and append the location information to the report.
The report triggered by a WTRU may include identity information.
Identity information may include the identity of the detected
out-of-coverage WTRU and/or the identity of the WTRU transmitting
the message (e.g., on the synchronization channel). The identity
may include a WTRU specific ID, a ProSe ID, a ProSe Group ID, a
ProSe Application ID, and/or the like. The report triggered may
include information related to one or more service (e.g., one or
more service identities) for the detected out-of-coverage WTRU
and/or for the WTRU transmitting the message. This information may
be used, for example, to establish a relay service.
The report may include the specific plurality of resources,
sub-frames and/or duration over which it may expect to receive data
and/or receive data (e.g., as determined by control message,
scheduling assignment, broadcast message, etc.)
The report triggered by a WTRU may include information relating to
whether an out-of-coverage WTRU is present and/or absent. An
indication when the in-coverage WTRU detected an out-of-coverage
WTRU requesting and/or providing PS service, an indication when the
in-coverage WTRU stops detecting the out-of-coverage WTRU (e.g.,
using measurements), and/or an indication when the out-of-coverage
WTRU stops requesting relay service and/or when the WTRU detects a
D2DSS from a neighboring WTRU, may be included in the report.
SFN (system frame number) and/or a timer reference may be used.
The report triggered by a WTRU may include information relating to
the reason for triggering the transmission of the report, the
request, and/or the transmission message (e.g., over a
synchronization message). The reasons to trigger a report may
include a request to initiate ProSe discovery and/or communication
for devices that may be operating in another frequency, detection
of a neighboring WTRU to initiate communication with, a neighboring
WTRU is no longer available, a new WTRU is detected, a change of
pattern and/or configuration request, a request to stop a ProSe
service, and/or the like.
Triggers may be provided. The WTRU may trigger a report, a request
for a pattern, and/or the transmission of a pattern (e.g., over a
synchronization message) based on the configuration. The WTRU may
initiate the transmission when it receives L3 signaling that
requests the WTRU to initiate a report and/or message transmission,
and/or when the WTRU is configured for such reporting and another
trigger initiates transmission of the report. Signaling may be
specific to a D2D and/or prose service (e.g., communication and/or
discovery) and/or may be WTRU-specific (e.g., applicable to any
identities).
Triggers for the report may be event-based. For example, the
trigger may be based on detection of a neighboring WTRU, a
neighboring WTRU leaving, a request to initiate a ProSe service
and/or initiate discovery, a change of pattern and/or resource
allocation used by neighboring WTRU, and/or the like.
The report may be triggered when the in-coverage WTRU detects an
out-of-coverage WTRU. The WTRU may detect the neighboring WTRU
based on a received D2DSS, a synchronization message, and/or data
received from the neighboring WTRU requesting a connection (e.g.,
solicited and/or unsolicited mode) and/or a WTRU performing PS
communication with which the in-coverage WTRU can communicate with
(e.g., the WTRUs belong to the same group and/or is allowed to
communicate according to the ProSe configurations). The report may
be triggered when an in-coverage WTRU detects the out-of-coverage
WTRU is no longer available and/or the out-of-coverage WTRU is no
longer requesting the service.
The WTRU may trigger a request and/or report when an application
request from a server to initiate a ProSe service is received. The
request and/or a pattern request and/or report from an in-coverage
WTRU may be to enable the WTRU to detect and/or discover an
out-of-coverage WTRU. The network may configure the WTRU for
additional reporting, for example, once the neighboring WTRU has
been detected and/or report to the network a request for
opportunities to communicate with the discovered WTRU. The WTRU may
trigger a report when it determines that a neighboring WTRU has
changed the pattern and/or the resource allocation.
Triggers may be based on measurements and/or other detected WTRUs.
The WTRU may trigger a report, a request for a pattern, and/or the
transmission of a pattern (e.g., over a synchronization message)
when connected to a higher priority synchronization source and/or
when the WTRU detects another WTRU transmitting a synchronization
originating from a lower priority source synch (e.g., a first WTRU
is connected to an eNB and detects a second WTRU that is sending a
synch signal and is connected to another WTRU and/or another synch
source). A trigger may be when the WTRU detects a second WTRU which
is not connected to an eNB. A trigger may be when the WTRU detects
a second WTRU operating on a frequency other than its frequency of
operation. A trigger may be when the WTRU detects a second WTRU
that belongs to the same group (e.g., the second WTRU is allowed to
communicate with the first WTRU). A trigger may be when the WTRU
receives data from a second WTRU and determines that the WTRU is
not in the coverage of the eNB (e.g., this may use an indication in
the SA that the WTRU is not in coverage if there is not a D2DSS,
SCI, SSS, other control signal and/or a message). A trigger may be
when the WTRU detects different transmission patterns from
different synchronization sources.
Triggers for the report may be periodic. The WTRU may initiate
reporting periodically, for example, if (e.g., only if) there is
one or more (e.g., possibly configurable number of) transmissions
applicable to the reporting period. The reporting may be stopped
when the WTRU detects that the out-of-coverage WTRU is no longer
available (e.g., based on measurement) and/or the out-of-coverage
WTRU stops requesting the service.
Triggers for the report may be aperiodic. The WTRU may initiate
reporting from the reception of control signaling that requests
that the WTRU perform reporting. Signaling may be received from a
network node and/or may be dedicated signaling and/or signaling
applicable to a plurality of WTRUs (e.g., received on a
broadcasting channel and/or on a common control channel).
The WTRU may transmit the report using L2 (e.g., MAC) signaling
(e.g., as a MAC Control Element), as L3 (e.g., RRC) signaling
(e.g., as a RRC PDU as part of a reporting procedure), and/or as
higher layer signaling (e.g., such as NAS signaling and/or
application signaling). For example, the WTRU may receive control
signaling on the PDCCH (e.g., an aperiodic request) that may
trigger such reporting. The WTRU may assemble the report as a MAC
control element and/or include it in an uplink transmission (e.g.,
its next uplink transmission). The eNB may be the endpoint of the
reporting procedure.
The WTRU may receive a request on a signaling radio bearer (SRB) as
an RRC PDU that triggers such reporting. The WTRU may assemble the
report as a RRC PDU and/or make it available for transmission on
the concerned SRB.
The WTRU may trigger reporting at the application level. For
example, the WTRU may assemble an application layer control packet
and/or make it available for transmission, for example, as a RRC
PDU and make it available for transmission on the concerned SRB
(e.g., in case NAS is used) and/or as a user plane data and make it
available for transmission for a corresponding DRB. The ProSe
and/or the application server may be the endpoint of the reporting
procedure.
The WTRU may trigger reporting. If the WTRU is in RRC IDLE mode,
the WTRU may initiate a transition to CONNECTED mode and/or
transmit the report according to the applicable signaling method.
The WTRU may remain in IDLE mode and/or delay the transmission of
the report until it moves to CONNECTED mode, for example, if RRC
and/or a higher layer protocol is used.
One or more of the following actions may be performed upon
reception of a report. The network and/or controlling node that
receives a report may analyze the resource pool information and
perform one or more of the following, for example, from reports
received from multiple sources. The network and/or controlling node
may determine which resource it may allow the in-coverage WTRU to
communicate within the resource pool. The network and/or
controlling node may initiate a procedure that reconfigures the
resources for one or more WTRUs. The network and/or controlling
node may use this information to avoid scheduling the WTRUs in the
given resources and/or time periods. For example, the eNB may
determine a gap pattern for the in-coverage WTRU and configure the
WTRU with the gap pattern.
Upon receiving a report, the eNB may determine, provide, and/or
configure a gap and/or time pattern for the WTRU. The gap pattern
may be a bitmask and may indicate the TTIs when the WTRU may not be
scheduled for normal communications and/or the pattern may
correspond to a period, cycle, and/or duration within a period
(e.g., each period) the WTRU may not be scheduled for communication
with the eNB. Upon receiving a report, the eNB may analyze the
requested gap pattern and if it is not deemed efficient, the eNB
may provide the WTRU with a new gap pattern.
The WTRU may use the gap pattern to switch to the out-of-coverage
link with the neighboring WTRU. The WTRU may send the gap pattern
to the out-of-coverage WTRU and/or the new gap pattern received
from the eNB to the out-of-coverage WTRU.
The eNB may remove the gap configuration, for example, when the
report includes an indication informing the eNB that the
out-of-coverage WTRU is no available and/or no longer requesting
the service.
Network resource management may be provided. The network may
allocate an amount of resources for D2D discovery WTRUs. If a
neighbor eNB shares the same resources, the chance that two D2D
WTRUs in proximity use the same resource to transmit discovery
signal may be high, for example, since there may be limited
resources. With proper resource management by the network,
interference and/or collisions may be avoided and/or mitigated
through coordination between eNBs and/or centralized control of
discovery resources. The network may manage resource management by,
for example, determining which resources may be allocated, to which
D2D WTRU the resources may be allocated, and/or how the WTRU
determines the resources to select to transmit (e.g., to transmit a
discovery signal or a D2D communication).
D2D WTRUs may select resources for transmitting a discovery signal
(e.g., D2D message). The monitoring D2D WTRUs may monitor the
resources (e.g., all the resources) for discovery, for example, as
allocated by the network. There may be more than one type of
discovery, for example, which may be based on network allocation of
resources to the WTRU. The network may allocate resources to one or
more D2D WTRUs on a non-WTRU specific manner. For example, a WTRU
(e.g., each WTRU) may select the resource to transmit from a set of
resources (e.g., a resource pool) allocated by network. The network
may allocate resources to one or more D2D WTRUs on a WTRU specific
manner. For example, a WTRU (e.g., each WTRU) may be scheduled with
dedicated resources to transmit a discovery signal.
The resources may be defined as a set of PRBs and/or subframes
which may be used for discovery. D2D WTRUs under the same eNB may
not create interference to each other since the network may
schedule the resource for each WTRU without any collision (e.g., as
in Type 2 D2D discovery). Without any coordination and/or central
control of neighbor eNBs, collisions may occur at the border of two
eNB areas. The network may not have any knowledge about the
resources used by each D2D WTRU for transmission. Without proper
allocation of resources, there may be many collisions within the
same eNB area and/or the WTRU under an eNB may cause interference
to other WTRUs under neighbor eNBs.
A WTRU at cell center may refer to a WTRU that is close to the
center of the cell to which it is associated (e.g., distance
between WTRU and eNB may be less than a threshold). A WTRU at cell
edge may refer to a WTRU that is close to the edge of the cell to
which it is associated (e.g., distance between WTRU and eNB may be
greater than a threshold). The WTRU may be associated to a cell,
for example, if the cell is the WTRU's serving cell (e.g., when the
WTRU is in Connected Mode), if the cell is the closest cell (e.g.,
in terms of signal strength, for example indicated by RSRP) to the
WTRU, and/or if the cell is the cell that the WTRU camps on (e.g.,
in Idle Mode).
A WTRU may be configured when it is located at cell center, for
example, by measuring the signal from one or more eNBs. For
example, a WTRU may be configured to determine that it is at cell
center by comparing the measured RSRP value of its associated cell
to a threshold. If the measured RSRP value is above a threshold
(e.g., the signal power is above a threshold), the WTRU may
determine that it is located at or near cell center. A WTRU may
determine that it is at cell center by comparing the measured RSRP
value of its associated cell (e.g., primary cell) to a measured
RSRP value of one or more cells (e.g., cell(s) adjacent to the
primary cell). The WTRU may determine that it is located at cell
center, for example, if it determines that the RSRP value of its
associated cell (e.g., primary cell) is larger than a value (e.g.,
preconfigured value), for example, of RSRP measurements from one or
more cells (e.g., adjacent cell(s)). For example, the WTRU may use
hysteresis (e.g., and/or time to trigger, make measurement for a
period of time, and/or the like) in determining whether or not it
is at cell center, for example, to avoid an undesirable ping-pong
effect. A WTRU at cell edge may refer to a WTRU which is close to
the edge of the cell to which it is associated. Methods similar to
those described for determining whether or not a WTRU is at cell
center may be used by a WTRU to determine whether or not it is at
cell-edge. For example, a WTRU may determine that it is located at
cell edge if it determines that the RSRP value of its associated
cell is smaller than a value (e.g., preconfigured value).
A D2D WTRU may be allocated with a set of resources (e.g., resource
pool) to transmit a discovery signal. The WTRU may use one or more
resources to start transmitting. If the network fully schedules the
WTRU with the resources for transmission, then the interference
caused by collisions may be avoided through resource
orthogonalization, which for example, may mean that the WTRU may
use its own dedicated resources to transmit and/or the resources
may not overlapped in time and/or frequency. If the WTRU is
allocated (e.g., only allocated) with a set of resources for
transmission and/or the WTRU selects the resources autonomously,
two or more D2D WTRUs in proximity may select the same resource for
transmission, which for example, may cause collisions and/or
interference. In this case, the network may not know that the
collisions and/or interference are occurring.
One or more of the following may be performed, for example, to
minimize the chance that two D2D WTRUs in proximity select the same
resource for transmission.
The network (e.g., an eNB) may allocate resources for one or more
D2D WTRUs to select for transmission. The eNBs may share the same
resources and/or an eNB (e.g., each eNB) may use a set of different
resources, for example, for type 1 or mode 2 (e.g., WTRU selected)
resource allocation. An eNB may allocate resources (e.g., a subset
of resources) based on the WTRU location and/or measurements (e.g.,
cell center, cell edge, etc.), resource utilization in an area,
prose application priority, discovery process characteristics
and/or configuration, and/or the like.
FIG. 10 is a diagram of an example of resource allocation of
resources (e.g., discovery) across two eNBs, eNB A and eNB B. Type
1 discovery may refer to when the network allocates resources to
D2D WTRUs on a non-WTRU specific manner, for example, such that a
WTRU (e.g., each WTRU) may select the resource to transmit from a
set of resources (e.g., from a resource pool) allocated by network.
Type 2 discovery may refer to when the network allocates resources
to D2D WTRUs on a WTRU specific manner, for example, such that a
WTRU (e.g., each WTRU) may be scheduled with dedicated resources to
transmit a discovery signal. In FIG. 10, (A) may be used to denote
a first eNB, eNB (A), and (B) may be used to denote a second eNB,
eNB (B).
Type 1 and type 2 discovery may use different sets of resources
and/or the allocation of resources for type 2 discovery may be
taken from the same resource pool as used for type 1 discovery, for
example, as shown in example (a) of FIG. 10. For type 1 discovery,
eNBs may share the same set of resources for discovery signal
transmission. For example, eNB (A) and eNB (B) may use resource
pools 1002 for type 1 D2D transmission. For type 1 discovery, eNBs
may allocate different sets of resources for WTRUs at the cell
center and WTRUs at the cell edge, for example, as shown in the
example (b) of FIG. 10. For example, eNBs A and B may allocate the
same set of resources for WTRUs in the cell center (e.g., resource
pools 1004), and a different set of resources for cell edge WTRUs
(e.g., resource pools 1006). The set of resources (e.g., resource
pools) used for cell edge WTRUs may be the same across the
different eNBs, for example as illustrated in example (b) of FIG.
10.
An eNB (e.g., each eNB, for example, eNB A and eNB B) may allocate
different resource sets for WTRUs at the cell center and at the
cell edge, for example, as shown in the example (c) of FIG. 10. For
example, different eNBs (e.g., eNB A and eNB B) may share the same
set of resources for the cell center WTRUs. Different eNBs (e.g.,
eNB A and eNB B) may allocate different resource sets for cell edge
WTRUs. For example, eNBs (A) and (B) may use resource pools 1008 at
their cell centers. eNB (A) may use resource pools 1010 at its cell
edge. eNB (B) may use resource pools 1012 at its cell edge. eNB (A)
and eNB (B) may use different resource at their cell edges, for
example to avoid interference.
eNB (A) and eNB (B) may use the same resource pools 1002 for type 1
communication, for example as shown in example (d) of FIG. 10. eNB
(A) and eNB (B) may use different resource pools for type 2
communication. For example, eNB (A) may use resource pools 1014 and
eNB (B) may use resource pools 1016 for type 2 communication, as
exemplified in examples (a), (b) and (c) of FIG. 10. eNB (A) and
eNB (B) may use the same resource pools 1018 for type 2
communication, as illustrated in example (d) of FIG. 10.
The eNB may allocate a different set of resources for different
application priorities. For example, a different set may be
available for WTRUs transmitting a signal from a higher priority
application and/or another set of resources may be available for
transmission from a lower priority application. The priority of the
applications may be configured by the network, a ProSe server,
and/or may be preconfigured. The discovery process characteristics
may be configured by the network, the ProSe server, and/or may be
preconfigured. Discovery process characteristics may refer to, for
example, the type of discovery process, the type of application
(e.g., public safety or commercial), the type of method (e.g.,
open/restricted discovery), the type of QoS characteristics,
latency of transmission, rate of transmissions or message
generation, and/or the like.
An eNB may achieve resource coordination. To allow the network to
allocate different sets of resources to D2D WTRUs, coordination
across different eNBs may be provided and/or a centralized
coordinator may be in charge of the resource management between
different eNBs.
Inter-eNB coordination of resources may be provided. The different
eNBs may exchange the sets of resources allocated to D2D WTRUs, for
example, via the X2 interface. For example, one eNB may send an X2
signal to a neighbor eNB(s), which may indicate a set of resources
allocated for its D2D WTRUs (e.g., resources at the cell center
and/or resources for D2D WTRUs at the cell edge). The neighbor
eNB(s) may allocate resource sets to its D2D WTRUs based on this
information. For example, the neighbor eNB(s) may share the same
set of resources for D2D WTRUs at cell center, and/or may use
different sets of resources for WTRUs at cell edge, for example, as
shown in the example (c) of FIG. 10.
Different eNBs may exchange the resource information, for example,
if the sets of resources allocated remain the same during a period.
If the eNB changes the resources allocated to WTRUs, the eNB may
send such information to its neighbor eNBs. Neighbor eNBs may
adjust the resources to allocate, for example, when an eNB receives
a report from the WTRU and/or determines that more resources will
be allocated. The eNB may inform the neighbor eNBs of such
changes.
Centralized resource management may be provided. Neighbor eNBs in
one area may be connected to a central node. The centralized node
may control the resource management among one or more neighbor
eNBs. The centralized node may allocate an eNB with the proper sets
of resources (e.g., a plurality of resource pools). For example,
the centralized node may allocate adjacent eNBs with the same set
of resources for the D2D WTRUs at the cell center and different
sets of resources for D2D WTRUs at the cell edge, for example, as
shown in the example (c) of FIG. 10.
eNB A and eNB B may be assigned a first resource pool 1008 to use
at or near the center of their respective cells, for example, as
illustrated in example (c) of FIG. 10. The eNB A and eNB B may use
the first resource pool 1008 concurrently at their cell centers
without causing significant interference because a distance between
the cell centers may be greater than a threshold distance in which
reuse causes interference. eNB A and eNB B may be assigned
different resource pools to use at or near their cells edges, for
example, as illustrated in example (c) of FIG. 10. For example, eNB
A may be assigned a second resource pool 1010 and eNB B may be
assigned a third resource pool 1012. eNB A and eNB B may not use
the same resource pool at their cell edges because their cell edges
may overlap or a distance between their cell edges may be less than
a threshold distance in which reuse causes interference.
One or more WTRUs may select a set of resources (e.g., a resource
pool) to use for D2D communication (e.g., transmission or
reception). A WTRU being served by eNB A may select a resource pool
from a plurality of resource pools to send information using D2D
communication, for example, as illustrated in example (c) of FIG.
10. A WTRU being served by eNB A may select the first resource pool
1008, for example when the WTRU is at or near the center of the
cell being served by eNB A. A WTRU being served by eNB A may select
the second resource pool 1010, for example when the WTRU is at or
near the edge of the cell being served by eNB A. A WTRU being
served by eNB B may select the first resource pool 1008, for
example when the WTRU is at or near the center of the cell being
served by eNB B. An example of this is illustrated in example (c)
of FIG. 10. A WTRU being served by eNB B may select the third
resource pool 1012, for example when the WTRU is at or near the
edge of the cell being served by eNB B.
The set of resources to be used by a WTRU for transmission may be
autonomously determined by the WTRU and/or explicitly configured by
the network, for example, based on one or more criteria. The
resource set selection criteria may be a function of one or more of
the following measurements and/or criteria determined by the
transmitting WTRU.
The resource selection (e.g., resource pool selection) may be based
on RSRP measurement(s). The RSRP measurement of the serving cell,
the eNB in which the WTRU is camped in idle mode, and/or the RSRP
from a neighboring eNB may be used for resource selection. For
example, a WTRU being served by eNB A may determine a RSRP
measurement and select a resource pool from a plurality of resource
pools based on the RSRP measurement.
A WTRU may determine a RSRP measurement of the serving cell. The
WTRU may compare the measured RSRP of the serving eNB to a
threshold (e.g., preconfigured threshold). For example, if the
measured RSRP is larger than a threshold, the WTRU may select from
the set of the corresponding resources (e.g., resources configured
for WTRUs that have an RSRP larger than a threshold). If the
measured RSRP is less than the threshold, the WTRU may select from
the other set of resources that are for WTRUs with RSRP smaller
than the threshold. For example, a WTRU being served by eNB A may
determine a RSRP measurement of a cell being served by the eNB A.
The WTRU may select the first resource pool 1008, for example when
the RSRP measurement is greater than a threshold. The WTRU may
select the second resource pool 1010, for example when the RSRP
measurement is less than the threshold.
A WTRU may use a RSRP measurement from a neighboring eNB to select
a resource pool. For example, a WTRU being served by eNB A may use
a RSRP measurement of a cell that is being served by eNB B (e.g., a
neighboring cell, for example an adjacent cell). The WTRU may
determine that it is proximate to a neighboring cell when the RSRP
measurement of the neighboring cell is above a threshold. A WTRU
being served by eNB A may select the second resource pool 1010, for
example when the RSRP measurement of a neighboring cell (e.g., a
cell being served by a neighboring eNB, eNB B) is above a
threshold. The WTRU may determine that it is distal from a
neighboring cell when the RSRP measurement of the neighboring cell
is below a threshold. A WTRU being served by eNB A may select the
first resource pool 1008, for example when the RSRP measurement of
a neighboring cell (e.g., cell being served by eNB B) is below a
threshold.
Different resource sets (e.g., resource pools) may be configured to
be used for different RSRP ranges. For example, the first resource
pool 1008 may be associated with a first range of RSRP values and
the second resource pool 1010 may be associated with a second range
of RSRP values. The first range of RSRP values may include RSRP
values above a threshold and the second range of RSRP values may
include RSRP values below the threshold. A WTRU may select the
first resource pool 1008, for example when the RSRP measurement is
within the first range of RSRP values. The WTRU may select the
second resource pool 1010, for example when the RSRP measurement is
within the second range of RSRP values. A range of RSRP values may
include a low RSRP threshold that indicates a lower limit of the
range and a high RSRP threshold that indicates a higher limit of
the range. A WTRU may determine that a RSRP measurement is within
the range of RSRP values when the RSRP measurement is between the
low RSRP threshold and the high RSRP threshold (e.g., greater than
the low RSRP threshold and less than the high RSRP threshold). A
range of RSRP values may be open-ended. For example, a RSRP range
may have one (e.g., only one) limit, (e.g., only a lower limit or
only a higher limit). A RSRP threshold may be a low RSRP threshold
of an open-ended range of RSRP values or a high RSRP threshold of
the open-ended range of RSRP values.
The WTRU may report the measurements (e.g., a RSRP measurement)
based on a triggering criteria to the serving eNB (e.g., eNB A).
The eNB may configure and/or indicate the WTRU with the set of
resources. For example, the eNB may indicate to the WTRU that the
first resource pool 1008 is associated with a first range of RSRP
values and the second resource pool 1010 is associated with a
second range of RSRP values. The eNB may indicate the resource
pool(s), RSRP range(s) and/or RSRP threshold(s) via radio resource
control (RRC) signaling. For example, the eNB may send a
configuration to the WTRU. The configuration may identify the
resource pool(s), RSRP range(s) and/or RSRP threshold(s).
The WTRU may compare RSRP from its serving eNB and/or one or more
neighbor eNBs. For example, a WTRU being served by eNB A may
compare RSRP measurements of the cells being served by eNB A and
eNB B. The network may configure two or more sets of resources for
D2D WTRUs in the center of eNB area and in the edge of the eNB
area. For example, eNB A may determine that the first resource pool
1008 be used at or near cell center and the second resource pool
1010 be used at or near cell edge.
The WTRU may determine which set of resources (e.g., which resource
pool to select from a plurality of resource pools) to select as a
function of the RSRP of the serving eNB and/or one or more
neighboring eNBs. For example, a WTRU being served by eNB A may
select one of the first resource pool 1008 or the second resource
pool 1010 based on a RSRP measurement. For example, the WTRU may
select resource pool 1010 (e.g., the resources for cell center)
when the measured RSRP of the serving eNB (e.g., eNB A) is larger
than the RSRP of one or more neighboring eNBs (e.g., eNB B), for
example, by a certain value and/or for a period of time. For
example, the WTRU may select the first resource pool 1008 when a
difference between the measured RSRPs of eNB A and eNB B exceeds a
threshold. Otherwise, the WTRU may select from the other set of
resources (e.g., second resource pool 1010). For example, the WTRU
may select the second resource pool 1010 when the difference
between the measured RSRPs of eNB A and eNB B is below a
threshold.
The WTRU may report the criteria to the serving eNB (e.g., eNB A).
For example, the WTRU may send a RSRP measurement to eNB A. The eNB
may configure the WTRU with the set of resources to select. For
example, the eNB A may configure the WTRU to select a resource pool
by sending a configuration to the WTRU. The configuration may
indicate a resource pool that the WTRU may use based on the RSRP
measurement. For example, WTRU may report `1` if the RSRP from the
serving eNB (e.g., eNB A) is larger than that from one or more
neighbor eNBs (e.g., eNB B), for example, by a value and/or for a
period of time, and the WTRU may report `0` otherwise. An eNB
(e.g., eNB A) may configure a WTRU to select a cell center resource
pool (e.g., first resource pool 1008) when the WTRU reports `1`. An
eNB (e.g., eNB B) may configure a WTRU to select a cell edge
resource pool (e.g., second resource pool 1010) when the WTRU
reports `0`.
The resource selection may be based on the path loss to the serving
eNB and/or to one or more of the neighboring eNBs. The WTRU may
compare the measured path loss to the serving eNB to a threshold
(e.g., a predefined threshold), for example, similar to RSRP
measurements. The WTRU may select the set of resources to choose
from based on the comparison result and/or the WTRU may compare the
path loss to the serving eNB and/or one or more neighbor eNBs. The
WTRU may select from the set of resources for cell center WTRUs
(e.g., first resource pool 1002) if the path loss to serving eNB
(e.g., eNB A) is less than that to one or more neighbor eNBs (e.g.,
eNB B). Otherwise, the WTRU may select from the set of resources
for cell edge WTRUs (e.g., second resource pool 1010). The WTRU may
report the measurement to the eNB based on a triggering criteria.
The eNB may configure the resource set to use.
The resource selection may be based on the timing advance value to
the serving eNB and/or to the neighboring eNBs. For WTRUs in
connected mode, the timing advance value to its serving eNB and/or
one or more neighbor eNBs may be used as a criteria to select the
resource set. For example, if the timing advance value in the
serving eNB is less than a threshold, the WTRU may select the
corresponding configured resource (e.g., when the given criteria is
met). Otherwise, the WTRU may select from another set of resources.
The WTRU may report to the eNB based on the comparison results of
one or more timing advance values.
The resource selection may be based on the measured energy level on
one or more (e.g., a sub-set) of allowed discovery resources. The
WTRU may determine the set of resources to select from and/or may
report to the eNB based on the measured resource utilization on one
or more (e.g., a subset) of discovery resources. Resource
utilization may be determined, for example, by measuring the amount
of energy and/or by monitoring control signaling and/or discovery
signaling in the resources of interest, for example, as described
herein.
The WTRU may perform measurements (e.g., energy level on the
resources within a set) on one or more sets of resources and use
the results of the measurements to determine which resource set to
use. The WTRU may select the resource set in which the measured
resource utilization is the lowest (e.g., the lowest energy level
was detected across the resources (e.g., all resources) in the set
over one measurement and/or over a number of measurements).
Resource selection (e.g., initial resource selection) may be
performed based on such measurements and/or the WTRU may randomly
select a resource across the available resource sets (e.g., from a
plurality of resources in a resource pool). Resource selection
(e.g., initial resource selection) may be based on a network
configured priority order and/or based on other measurements, for
example, as described herein. Once a resource selection (e.g., an
initial resource selection) is performed, the WTRU may change a
resource set, for example, if the measured energy level across
resources (e.g., all the resources) is higher than a threshold, for
example, for a period of time. The WTRU may select a resource set
(e.g., a new resource set) based on the measured energy in another
set of resource. For example, the WTRU may select the resource set
with the lowest energy level, the WTRU may randomly select a
resource set, and/or the WTRU may select the next highest priority
set of resources. The WTRU may select a set of resources if another
set of resources has a lower average resource utilization across
its resources, for example, by a threshold and/or for a period of
time. If the resources are occupied on one or more (e.g., all)
resource sets, the WTRU may send a report to the network.
The resource selection may depend on the priority of the
application. The WTRU may be configured with a priority (e.g., a
Prose application priority). One or more resource sets may be
configured with one or more associated application priority
classes. The WTRU may determine which resource set to use based on
the priority of the application for which a discovery signal is
being transmitted. The WTRU may select the resources with the
highest available priority that are equal to or lower than the
configured application priority.
The resource selection may depend on one or a combination of the
configured characteristics of a ProSe application (e.g., for
discovery and/or for communication). For example, resource
selection may depend on the type of application, use of
application, public safety or commercial, QoS characteristics
(e.g., latency, rate, etc.), power characteristics/requirements,
type of discovery (e.g., open/restricted) or Model A vs. Mode B
discovery, type of communication (e.g., unicast, multicast, or
groupcast), etc.
The resource selection for communication may be performed to select
one amongst the multiple configured SA resource pools or data
transmission pools.
The WTRU may be configured with one or a combination of
characteristics. Each resource pool may be configured with one or a
combination of characteristics. The WTRU may select a resource set
or a set of resources that are configured with the same
characteristic as the ProSe application in the WTRU. For example,
if the WTRU is configured with a public safety type of application,
the WTRU may select the set of resources that are configured for
public safety.
The WTRU may select a resource set that meets the power class
requirement and/or characteristic of the given application or set
of applications. The WTRU may select a resource set from the
available resources that is configured with the type of discovery
associated to the given application. The WTRU may select from a
resource set that allows the WTRU to meet one or more of the QoS
criteria, including for example, latency and/or rates. From the
configured set of resource, the WTRU may determine the resource set
that has the periodicity and/or number of D2D available subframes
for D2D transmissions that would allow the WTRU to meet the
requirements and/or rates.
The WTRU may select from a resource set that allows the WTRU to
meet one or more QoS criteria, including for example, a guaranteed
bit rate. For example, the WTRU may determine the resource set that
is configured to support a configured PBR or GBR of the logical
channel assigned to the D2D transmission packet.
Triggers to perform selection of resources (e.g., autonomous
selection of resources) and/or to initiate a report to the eNB may
be provided. The WTRU may perform resource selection and/or
reporting to the network when a discovery and/or communication
process is initiated (e.g., the first time when WTRU attempts to
select resources to transmit discovery signal), for example, when
the WTRU determines to transmit a discovery signal or message for
the first time. The WTRU may report the criteria the WTRU has to
meet and/or the characteristics of the eNB to the eNB based on the
measured results, for example, as described herein.
At the beginning of a (e.g., each) discovery occasion, the WTRU may
perform a measurement (e.g., RSRP measurement) and/or use the
measurement to select the appropriate resource set (e.g., resource
pool). The WTRU may utilize resources from this resource set for
the duration of the discovery process and/or for a configured time
period.
The WTRU may perform resource selection (e.g., dynamic resources
selection) according to one or more of the criteria defined herein,
for example, at every transmission. The WTRU may monitor the
resource set and/or measurements. If one or more of the conditions
described herein are met, the WTRU may change the resource set it
uses. The WTRU may trigger a report to the network when the
conditions described herein are met, for example, when WTRU
measured RSRP of its serving eNB is above the threshold (e.g., for
a duration of time) and/or is decreasing as it moves further from
the eNB. If the RSRP value drops to under the threshold, the WTRU
may send a report to the eNB indicating such changes and/or may
change (e.g., autonomously change) the set of used resources.
The WTRU may perform resource selection and/or reporting to the
network when the WTRU is configured by the network to send such
report, for example, which may be used for the network to decide
which set of resources and what characteristics may be allocated to
the WTRU.
The WTRU may perform resource selection and/or reporting to the
network when the WTRU cannot find an available set of resources to
select. For example, if all sets of resources are occupied based on
the measured energy level. The WTRU may select a resource set, may
be randomly performed across available resource sets, and/or based
on a network configured priority order. If the resource set is
selected based on a network configured priority order, the network
may broadcast a table indicating the priority order of one or more
of the resource sets.
Resources may be selected when the application and/or discovery
process meets different criteria. A set of resources (e.g., a
discovery resource pool, a SA transmission pool for communication,
a communication data transmission pool, etc.) may be configured
with an index that corresponds to one or a combination of the
different criteria that the WTRU is allowed to select from. For
example, an explicit mapping between an index and a criteria or
combination of criteria may be defined. The WTRU may determine the
associated index depending on its configured criteria (e.g., type
of application, power range, QoS, priority, bit rate, etc.).
Table 1 is a table that illustrates an example mapping of a three
bit index and associated criteria. The set of criteria that define
the resource usage may correspond to the type of application and/or
power range for which the resource set can be used. A mapping table
may be produced for different resource usage definition that
combine different set of desirable criteria and/or with a different
number of bits for the index number. For example, more bits can be
used if the priority criteria is included in the definition of the
resource usage.
TABLE-US-00001 TABLE 1 Example Mapping of a Three Bit Index and
Associated Criteria Index number Description of resource usage 000
Resource set can be used by WTRUs that have a commercial
applications 001 Commercial application and low power range 010
Commercial application medium power range 011 Commercial
application and high power range 100 Resource set can used by WTRUs
configured or that are transmitting public safety application type
101 PS and low power range 110 PS and medium power range 111 PS and
high power range
The discovery process and/or communication session may be
independently configured with the different criteria. The WTRU may
determine to which index the set of criteria maps. The WTRU may
select the resource set associated to that index. The WTRU may be
explicitly configured with an index. If no resources are configured
with the given index, the WTRU may determine the next resource set
that meets the configured criteria the best.
A discovery process and/or communication session may be associated
with more than one desired usage index (e.g., in a priority order).
The WTRU may be configured to match the offered usage index to one
or more of the desired usage index (e.g., in order of priority). If
that does not work, the WTRU may revert to a default resource
and/or a resource that is configured for any type of service.
The resource set may be configured with a resource index and with a
measurement criteria (e.g., RSRP threshold associated with
resource). Each criteria may be independently configured. Priority
amongst the criteria may be established
A resource set may be configured (e.g., explicitly and/or
independently configured) with one or more different criteria. For
example, a resource set may indicate whether it is for public
safety (PS) use, commercial use, or neither (e.g., resources may be
for any application type). In an example criteria, a resource set
may be configured with a power range (e.g., low, medium, high, or
none). None may imply that all the resources may be used for all
power ranges. For example, a resource set may indicate the type of
QoS it supports, the packet bit rate (e.g., PBR or GBR) it can
support, and/or the like.
The WTRU may select the first resource set(s) associated with a
first criteria (e.g., highest priority criteria). The WTRU may use
the next criteria, determined based on the order of priority, to
select the next set of resources within the first resource set and
so on. For example, the WTRU may first select the set of resources
associated for use with an application type (e.g., PS or
commercial). The WTRU may select resources that meet a set of power
range criteria. The WTRU may select the set of resources according
to the RSRP measurement and/or resource configuration.
The WTRU may select the set of resources associated with a
configured priority level. The WTRU may select the resource sets
with the highest priority level that is equal to or lower than the
WTRU configured application priority level. The priority level may
be a lower priority than the resources allowed to be used according
to the RSRP measurement. So the WTRU may select the set(s) of
available resources that meet the configured RRSP measurement
criteria and then select the resource with the higher priority
level that is equal to or lower than the application priority.
If the WTRU is unable to find a resource set with offered usage
index that matches the usage index of a given discovery process
and/or communication session, the WTRU may be configured with
guidelines on using a closest match resource set. For example, if
the WTRU is unable to find a resource set for short range
discovery, the WTRU may be configured to use resources from a
medium range resource set while respecting its maximum power
transmission requirement. For example, the WTRU may have rules to
select the resource set configured with a packet bit rate equal to
or higher than the packet bit rate of the radio bearer (e.g.,
logical channel) of the transmission packet.
A default pool may be configured that may be used for discovery
messages with any required usage index requirements. The WTRU may
select the default pool when no other match is found.
WTRU-autonomous resource control may be provided. The transmitting
WTRU may determine how many discovery transmissions (e.g.,
including 0) to perform in a given discovery occasion and/or time
period. By configuring the WTRU discovery transmission rate, the
network and/or system may adjust the amount of interference and/or
the service quality.
The WTRU may be configured with a fixed discovery transmission
rate. For example, the WTRU may be configured by the network with a
given discovery transmission rate. The WTRU may receive the
configuration via dedicated signaling (e.g., via RRC, NAS, from the
ProSE server, and/or the like). The WTRU may receive the
configuration via the broadcast channel (e.g., via one or more
SIBs). The configuration may identify the resource pool(s), RSRP
range(s) and/or RSRP threshold(s).
The WTRU may be configured with a discovery transmission rate, for
example, which may be parameterized using one or more of the
following. The WTRU may be configured with an average rate
expressed in a number of discovery transmissions per seconds. The
WTRU may determine how many discovery transmissions to perform in
one or more (e.g., a series of) discovery occasions to achieve the
rate. The WTRU may be configured to transmit the discovery signals
at regular intervals to achieve the rate. The WTRU may be
configured with a number of discovery transmissions for a specific
number of discovery occasions and/or specific time interval. For
example, the WTRU may be configured to transmit N transmit
discovery signals over N discovery occasions. The WTRU may be
configured to transmit N transmit discovery signal during a time
interval, for example, which may be specified in a number of frames
(e.g., Nframes) and/or absolute time (e.g., seconds).
The WTRU may be configured to repeat the discovery signal payload
during a discovery occasion, for example, when the rate permits.
This may happen, for example, when the rate is such that the WTRU
may transmit more than one discovery signal in one discovery
occasion.
The configured discovery transmission rate may be applicable to one
or more (e.g., all) discovery processes. The WTRU may be configured
with a discovery transmission rate specific to a (e.g., each)
discovery process.
The WTRU may determine the discovery transmission rate
autonomously. The WTRU may base its discovery transmission rate on
measurements of discovery resources. The WTRU may be configured
with a minimum discovery transmission rate and/or a maximum
transmission rate. The WTRU may be configured to measure the
resource utilization and update the current transmission rate
(e.g., current_discovery_rate) after a given measurement
period.
The WTRU may initialize the current_discovery_rate to a value
(e.g., predefined value). The WTRU may initializes the
current_discovery_rate to the minimum discovery transmission rate
configured. The WTRU may reset, re-initialize, and/or set to zero
the current_discovery_rate, for example, when one or more of the
following occurs. The WTRU may reset, re-initialize, and/or set to
zero the current_discovery_rate when the WTRU has not transmitted a
discovery signal for a configured duration of time. The WTRU may
reset, re-initialize, and/or set to zero the current_discovery_rate
when the WTRU receives a signal from the network. For example, the
signal may be a signal indicating a change of resources for
discovery (e.g., in which case the WTRU may re-initialize the
current_discovery_rate) and/or a signal indicating the WTRU to set
its current_discovery_rate to 0 (e.g., for a predefined amount of
time after which the WTRU may be configured to re-initialize the
current_discovery_rate). The WTRU may reset, re-initialize, and/or
set to zero the current_discovery_rate when the WTRU determines
(e.g., measures) that the discovery resources utilization level is
above and/or below a threshold, for example, for a configured
amount of time.
There may be one or more triggers for the WTRU to increase and/or
decrease the current_discovery_rate. The WTRU may increase the
value of the current_discovery_rate by an amount when the WTRU
determines that the resource utilization is below a threshold, for
example, for a period of time.
The WTRU may increase the discovery transmission rate by an amount
(e.g., the WTRU may double the discovery transmission rate). The
WTRU may be configured to not exceed the maximum rate
configured.
The WTRU may decrease the discovery transmission rate by an amount.
For example, the WTRU may decrease the discovery transmission rate
by an amount once for a period of time (e.g., every period of time)
during which the WTRU determines that the resource utilization is
above and/or below a threshold, for example, for a period of time.
The WTRU may decrease the discovery transmission rate by an amount
based on the activity state associated to one or more of its
discovery processes, for example, when the WTRU determines that it
has not performed a discovery transmission during an amount of
time. The WTRU may decrease the discovery transmission rate by an
amount based on network signaling. For example, the WTRU may
decrease the discovery transmission rate by an amount when the WTRU
receives network signaling via dedicated signaling (e.g., using a
DCI on (e)PDCCH masked by C-RNTI, by another configured RNTI, by L2
MAC signaling using a MAC Control Element, and/or the like). For
example, the WTRU may decrease the discovery transmission rate by
an amount when the WTRU may receive network signaling via the
broadcast channel (e.g., via one or more the SIBs).
The WTRU may halve the discovery transmission rate. The WTRU may
not decrease the rate below the minimum value configured.
The WTRU may determine the discovery resource usage based on the
energy level on discovery resources. For example, the WTRU may
measure the energy level on the discovery resources (e.g., when not
transmitting) and compare it to a threshold. The WTRU may determine
the discovery resource usage based on the number of successful
discoveries. For example, the WTRU may count the number of
successful discoveries and compare it to a threshold. The WTRU may
determine the discovery resource usage based on one or more SIBs.
For example, the WTRU may monitor one or more SIBs for indication
of resource utilization. The WTRU may read the resource utilization
from the one or more SIBs.
The WTRU may determine the resource utilization based on an
indication by the network, for example, signaled via one or more
SIBs. For example, the WTRU may monitor the one or more SIBs for a
discovery signal resource utilization overload indicator. The WTRU
may increase and/or decrease its discovery transmission rate (e.g.,
as described herein), for example, based on the value of the
overload indicator.
The WTRU may determine that one or more discovery resources are
dedicated (e.g., associated to different discovery processes by the
network) while one or more discovery resources are shared. The WTRU
may consider (e.g., only consider) the one or more discovery
resources that are shared in its determination of resource usage
level. The WTRU may apply the resulting transmission rate to
processes associated with shared resources (e.g., only to processes
associated with shared resources).
Interference mitigation via resource randomization may be provided.
The transmitting WTRU may select the actual transmission occasions,
for example, from a set of allowed discovery occasions, for
example, to randomize the system interference.
WTRU may randomly select a resource (e.g., the set of subframes)
over which to attempt D2D communication (e.g., discovery
transmission). The transmitting WTRU may determine the set of
subframes over which a discovery signal may be transmitted. The
WTRU may determine the number of subframes used for discovery
signal transmission (e.g., Nreq) over a number of discovery
subframes (e.g., Ndisc), for example, defined over a period of time
(e.g., over a discovery occasion cycle) based on its configuration,
for example, based on one or more of the following.
The WTRU may determine the number of subframes used for discovery
signal transmission based on the number of discovery processes
configured, the QoS and/or discovery transmission rate of a (e.g.,
each) discovery process, the maximum and/or minimum discovery
transmission rate configured and/or allowed per transmitting WTRU,
and/or the minimum number of subframes used by the WTRU to meet its
required QoS across the configured discovery processes.
The WTRU may select (e.g., randomly) Nreq subframes (e.g., a
resource) over the total number of subframes (e.g., from a
plurality of resources), for example, during a period (e.g., Ndisc
subframes), for example to perform and/or attempt D2D communication
(e.g., discovery transmission).
The WTRU may select the resource (e.g., subframe(s), PRB(s), etc.)
using a (e.g., predefined) randomization function, for example,
which may be initialized by a WTRU-specific value. This may ensure
that no two WTRUs select the same set of resources over time. The
WTRU may be configured with a pseudo-random sequence function
initialized with a seed based on a WTRU-specific value signaled by
the network and/or based on a WTRU-ID and/or part of a WTRU-ID
(e.g., IMSI, T-IMSI, C-RNTI, IMEI, etc.).
The WTRU may re-initialize the randomization function at a regular
interval, for example, every time the SFN wraps around and/or at
another time instant.
Time delay restrictions may be provided. For example, the WTRU may
be configured with a minimum delay and/or number of subframe
between two allowed discovery transmissions. This may be used to
exploit time diversity of the channel. When selecting (e.g.,
randomly) Nreq subframes (e.g., a resource) over the total number
of subframes (e.g., from a plurality of resources) during a period
(e.g., Ndisc subframes) to perform and/or attempt discovery
transmission, the WTRU may ensure that no two selected subframes
violate the minimum delay requirement. This may be performed, for
example, by discarding invalid configurations when they occur
and/or re-attempting selection until it meets the requirements.
The WTRU may selects one or more (e.g., a set) of subframes over
which to attempt discovery transmission, for example, based on
predefined hopping pattern. The WTRU may be preconfigured with one
or more set of subframe hopping patterns. A (e.g., each) hopping
pattern may define a set of subframes over which the transmitting
WTRU may transmit a discovery signal, for example, over a period of
time (e.g. over a discovery occasion cycle).
The WTRU may determine the number of subframes used for a discovery
signal transmission (e.g., Nreq) over a number of discovery
subframes (e.g., Ndisc), for example, as described herein. The WTRU
may select the family of hopping pattern for which the hopping
pattern (e.g., every hopping pattern) allows for Nreq discovery
subframes transmission, for example, based on the value of Nreq.
The WTRU may select one or more of the hopping patterns from that
family, for example, based on a random function. For example, the
WTRU may select the hopping pattern using an index generated by a
pseudo-random function. The pseudo-random function may be
initialized with a seed derived, for example, as described
herein.
Although features and elements are described with reference to LTE
(e.g., LTE-A) and LTE terminology, the features and elements
described herein may be application to other wired and wireless
communication protocols, for example, HSPA, HSPA+, WCDMA, CDMA2000,
GSM, WLAN, and/or the like.
Although features and elements are described above in particular
combinations, one of ordinary skill in the art will appreciate that
each feature or element can be used alone or in any combination
with the other features and elements. In addition, the methods
described herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable medium
for execution by a computer or processor. Examples of
computer-readable media include electronic signals (transmitted
over wired or wireless connections) and computer-readable storage
media. Examples of computer-readable storage media include, but are
not limited to, a read only memory (ROM), a random access memory
(RAM), a register, cache memory, semiconductor memory devices,
magnetic media such as internal hard disks and removable disks,
magneto-optical media, and optical media such as CD-ROM disks, and
digital versatile disks (DVDs). A processor in association with
software may be used to implement a radio frequency transceiver for
use in a WTRU, WTRU, terminal, base station, RNC, or any host
computer.
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